4. The injection of it, followed by immersion, preserves the object
well enough for the space of two or three months, but putrid
decomposition attacks the thoracic and abdominal viscera, as well as
the brain and thick muscles, at the end of this time.
5. A subject injected with alcoholic sublimate, then opened, emptied,
and macerated, afterwards exposed to the air, dries easily;[7] but
it assumes a deep gray colour, and the tissues become hardened to
such a degree, that it hardly preserves a human form. These are the
rigorous results of experience. In the preservation by the aid of
deuto-chloride, one portion of the subject is sacrificed to preserve a
few remains; the most noble of all the organs, the brain, the throne
of thought, cedes its importance to a few bones clothed with dried
muscles, and a skin transformed, and not easily known again.
[7] The deuto-chloride of mercury, like the salts of copper, arsenic,
iron, &c., are decomposed by gelatine, forming a new imputrescible
compound. The preservation is much more sure if a large quantity of
alcohol is used in drying the corpse.
These are but feeble advantages, and paid for much too dearly; for the
inconveniences and dangers of this mode of preparation, appears to us
sufficient to cause them to be abandoned.
It is very expensive, dangerous for the operators; it alters the
instruments, and the bodies which receive the influence of its
emanations. Recently, during the embalming of some great personage, all
the gildings of a vast saloon, where the operation was performed, were
destroyed by the action of the deuto-chloride.
Nevertheless, the embalmings made with this substance, and of which the
three first observations cited in this chapter are the most remarkable
examples in our knowledge, afford the most decided expressions of the
advanced state of the art.
What are the ameliorations resulting from our discoveries? They are as
follows: 1. A substance easy to manage without danger to the operator,
without any inconvenience to the instruments and other metals, is
substituted for the sublimate; 2. The operation can be entirely
finished in half an hour; 3. The numerous incisions, the mutilations,
the subtraction of the viscera, &c., the prolonged maceration, are
replaced by an injection through an opening of some lines in extent;
4. In place of a substance discoloured, leathery, and dried, reserving
more or less the human form, my process preserves the subject, such as
it is, at the moment of death, with the colour and suppleness proper
to each tissue;[K] 5. Finally, the expense which, by the preceding
method, amounts to from four hundred to two thousand dollars, need not
now exceed sixty dollars. Thus a body may be indefinitely preserved
for a sum less than the price of a leaden coffin furnished by the
undertakers, _a coffin which accelerates the putrid decomposition, in
place of preventing it_.
[K] When we visited and gave an accurate examination of the numerous
embalmed objects in M. Gannal’s museum, we did not observe any
specimens that had been finished long enough to dry, displaying such
perfection as that here stated.--_Tr._
I confine myself here to the announcing of some results obtained by my
predecessors; for previous to entering into details of the experiments
which I have tried, it remains for me to trace the picture of the means
employed down to our period for the preparation and preservation of
pieces of normal anatomy, pathological anatomy and natural history.
This will form the subject of chapter VII.
When I shall have made known the whole of the resources of this other
branch for the preservation of animal matters, each one can form an
accurate opinion, after a complete knowledge of the facts, of the part
which belongs to my labours, and of the place which they ought to
occupy in the scale of natural sciences.
CHAPTER VII.
METHODS OF PREPARING AND PRESERVING SUBJECTS OF ANATOMY, PATHOLOGY, AND
NATURAL HISTORY, PREVIOUS TO THE PROCESS OF GANNAL.
Among the investigations belonging to the domain of medicine, normal
anatomy and pathological anatomy occupy the first rank; they constitute
the necessary basis of exact study: all men of genius have experienced
this.
This conviction has been the source of the persevering efforts of
numerous distinguished savans, who reasonably supposed that they
would merit the esteem and gratitude of their species, if they could
succeed in composing collections of engravings, or artificial models,
representing the form, colour, &c., of each of the organs, or if they
could discover methods of preparation capable of preserving the organs
themselves with all the physical properties which they possessed at the
moment of death.
It is not necessary to enter into discussions upon the high importance
of these different kinds of investigations; for every one comprehends
it, and the gravest authorities have pronounced upon this matter.
Who does not know the vast importance which our illustrious Cuvier
attributed in the progress of the natural sciences, to him who first
conceived the idea of preserving objects in alcohol? It is perceptible,
indeed, at the first glance, that the most beautiful and valuable of
libraries for the physician and naturalist would be a collection of
artificial subjects; or still better, of all the organs of the bodies
of animals, and of man, skilfully prepared and preserved, without any
alteration of the properties which it is important to know.
It must be admitted that a collection in which all the organs would
be disposed in series, where they would be seen passing by their
successive degrees of increment and decrement, offering their
differences, individual and sexual, their points of contact and
separation in the various classes of the animal kingdom, their
anomalies, their pathological affections, their intimate structure,
& c., it must be admitted I say, that such a collection would be an
inexhaustible source of knowledge; it would acquire additional value by
the addition of a series of pieces representing the detailed anatomy of
each of the parts involved in surgical operations.
But this library, so eloquent and instructive, does it exist at the
present time? Do we possess the means of forming such? The examination
of the various processes, ought to furnish us with an answer to this
question; it will besides enable our readers to estimate for themselves
the part that our method may enjoy in the accomplishment of this object.
And first, in admitting the utility of _engravings_ of _models in
wax_, and in _artificial carton_,[L] in _white wood_, or in other
compositions kept secret by their authors, we feel that whatever may
be the accuracy of these different representations, they never can
afford but an incomplete idea of the thing represented. 1st. _Plates
and engravings_, so advantageous for reference, to recall the study
made upon the corpse, have lost their importance in proportion as
the means of obtaining dead bodies have become more easy: they are
calculated to render great service and contribute to the progress of
science in the fine anatomical works of Meckel, Lauth, Haller, Zinn,
Hunter, Cruikshank, Cowper, Vic-d, Azyr, and of numerous other learned
authors; at the present day, even, they are justly esteemed in the
great works of MM. Cloquet, Bourgerie, &c. (The plates of the work of
M. Bourgerie, are executed with remarkable care, and will form an epoch
in the history of anatomical works.) But they occupy a secondary place,
only to aid the memory; for of whatever good they may be, they must
always have many inconveniences: 1. They fatigue attention, because it
is necessary so often to multiply the figures, when it is requisite to
examine an object under all its aspects where it is of importance to
perceive it; 2. The organs are rarely seen of their natural dimensions;
3. Whatever may be the exactitude of the drawing, it is difficult to
form a just idea of the relief and dimension of the organs; 4. The
relations which they indicate are always incomplete; it is impossible
thus to represent all the organs in their position, and in their
natural relations.
[L] A composition of papier mache, with which Dr. Azoux has so
beautifully represented anatomical subjects.--_Tr._
2d. _Models in wax_, nearer to nature than plates, reproduces objects
with admirable truth for the eye, but for the eye only. They were
recently estimated of such importance, that courses on modelling were
introduced into the schools in many cities of France; nevertheless, it
cannot be concealed that pieces thus prepared leave much to be desired:
1. The relations of the organs which they indicate are very limited: 2.
It is necessary then to multiply them to infinity, if it be desirable
to represent under various points of view, the different points of
the human body, which is indispensable, in order to comprehend their
relations and connections: 3. And still the mind comprehends with
difficulty the totality of objects viewed in a great number of pieces:
4. They cannot be handled and displaced as is requisite for study,
without injury to them.
3d. _Artificial pieces_, which possess many of the inconveniences of
wax models, are more proper to give a knowledge of the parts, which
enter into the structure of man; nevertheless, if they be white wood,
like the subjects of Fontana, or in Carton, like those of Ameline, or
of M. Azoux,[8] they leave much to be learned of the properties which
are requisite to an accurate and complete knowledge of the parts.
Finally, these three means of communicating knowledge possess their
degree of utility, but they can never support a comparison with the
proper matter of the organs; they may serve to complete a museum, but
never to form one; so we content ourselves to mention them here, in
order to assign them a rank.
[8] The subjects prepared by M. Azoux, are however, more proper to
facilitate and extend the study of anatomy; they are far superior to
dried objects. It is desirable that every amphitheatre should possess
one of these subjects.
Anatomical pieces which place before the eyes the organs, themselves,
are then the elements, “par excellence,” for the formation of
collections, which are to serve as studies of normal anatomy, of
pathological anatomy, and of natural history, but, the preparation
and preservation of these pieces is a new science; we ought not
to be astonished at it, notwithstanding the advanced state of our
anatomical knowledge, if we reflect on the difficulties of all kinds,
which prejudice excited in our predecessors. It is stated, it is
true, that Ruysch, had discovered the means of preserving the dead
body, with _all the appearance of life, without drying, with florid
complexion, and supple limbs_. But, is this really the fact? and have
we not good reasons to doubt such assertions, since no collection of
anatomical pieces, prepared by this process, has descended to us, and
no explanation has confirmed our knowledge of them?
We may then conclude, that the means of preparing and preserving, does
not date much earlier than the commencement of the present century.
None of them, however, has had for object the preservation of the
entire subject: that which offers us the most numerous parts united
in the same preparation has only a reference to anatomy, properly so
called; it is the process of M. Swan, of England, given by him as a new
method of making dried anatomical preparations, preserving to them the
appearance and the advantages of fresh preparations, without possessing
the inconveniences of them; this process is, as we shall see, only
an application of the discovery of Chaussier, on the preservative
properties of the deuto-chloride of mercury. We give it here, before
passing in review the methods of preparation practised for each organ
or each tissue.
“In order to describe the manner of making these preparations, I shall
only take the arm by way of example.
“The member should be selected as clear from fat as possible. A
solution of two ounces of oxymuriate of mercury, in half a pint of
rectified spirits of wine, must be injected into the arteries, and the
day after make another injection with the same quantity of white spirit
varnish, to which must be added one-fifth part of turpentine varnish,
and a small quantity of vermillion. The limb should next be placed
in hot water, and remain there until it is sufficiently heated for a
coarse injection into the arteries, and even the veins if necessary. If
the veins are to be injected they had better be emptied of blood, with
water, before forcing into the arteries the solution of oxymuriate of
mercury, because there returns always by the veins some portion of this
injection which coagulate the contained blood, and hinders the coarse
injection from passing into the smaller branches.
“After the limb has been injected it may be dissected. Every time
the work is left, it is better that the parts uncovered, should be
enveloped in a linen cloth wet with water; and when the dissection is
recommenced a great advantage will be remarked, which is that the parts
injected with the solution of the sublimate will suffer very little
alteration in several days, and are found in the same state in which
they were left, whilst, by the common method, in one or two days, all
is so changed that there is little profit in seeing what has been
done, and if the dissection is long, they will scarcely be recognised
when finished.
“Another advantage is that it may be dissected any where, since the
preparation is without odour.
“When all the parts are uncovered, and all the fat and cellular
tissue has been removed, the member thus prepared must be put into
a solution of two ounces of oxymuriate of mercury, to one pint of
rectified spirits of wine, and let remain entirely covered with this
for at least fifteen days, for it cannot remain too long. A box of
oak, painted white and varnished is the best recipient for the limb,
whilst in solution; the cover must fit closely, in order to prevent the
evaporation of the spirits of wine.
“The member must be withdrawn every two or three days, and any
remaining cellular tissue is to be removed, and when returned to
the tub the part which previously touched the bottom must be placed
uppermost. The best thing upon which to place the preparation, when
withdrawn from the solution, is a butcher’s tray, after having been
well oiled; without this precaution the tray imbibes moisture, from
which results a great loss of the solution. When the limb has remained
long enough in the solution, it is to be taken out, to be painted and
varnished.
“Before proceeding to these operations, the member kept in a state of
extension, is suspended and dried, then endued with white varnish. On
the same day the nerves, the tendons, and tendinous expansions, ought
also to be varnished; which must be repeated once a day, for three
consecutive days. The fifth day, the tendons, ought to be covered with
a layer of yellow varnish, and white paint mixed in equal parts; this
operation is to be repeated the seventh, eighth, and ninth day. The
nerves, must also be endued, as often as necessary, with a mixture of
equal parts of white paint, and white varnish.
“As soon as the muscles have become stiff, they may be painted, taking
care that the nerves and tendons, are not touched by the paint. Nearly
a month after the limb has been withdrawn from the solution, those
of the nerves and tendons that are not sufficiently coloured should
be repainted and varnished, as often as may be judged necessary. But
always allowing a day’s interval between each application of paint and
varnish.
“These operations being finished, wash lightly the tendons and nerves
with boiled flax seed oil; this layer being dry, give a second over the
whole limb; finally, several layers of copal varnish will terminate
the operation. The first layer of copal varnish to be applied to the
arteries with a slight addition of vermillion, and of Prussian blue,
for the veins.
“In order to preserve the liver, it is necessary first to inject the
vena porta and excretory ducts with white varnish, to which has been
joined one-fifth of turpentine varnish, and some coloring matter, such
as red lead. Then make the coarse injection, after which the liver
is to be put into the solution for a least fifteen days; it is not
necessary to heat it before injecting. The ligaments are to be prepared
in the same manner as the tendons.
“We give below the paints, and varnishes, employed in the preceding
preparations:
1.--_White Varnish._
℞. Canada balsam, spirits of turpentine, _a.a._ 3 ℥.
Mastic Varnish. 2 ℥.
Put the whole in a bottle, and agitate until it is perfectly mixed.
2.--_Mastic Varnish._
℞. Powdered mastic. 4 ℥.
Dissolve in a pint of spirits of turpentine.
Agitate daily, until the mastic is dissolved.
3.--_Yellow Varnish._
Infuse one ounce of gum-gutta in powder in eight ounces of spirits of
turpentine for fifteen days; then, with equal parts of this clear drawn
liquor, Canada balsam, and mastic varnish, form the yellow varnish.
4.--_White Paint._
Three ounces of white lead, and an ounce of spirits of turpentine
serves to form it.
5.--_Paint for the muscles._
It is made of Lac, Prussian blue, and white varnish, to which is added
one quart of turpentine varnish.
6.--_Red Injection._
℞. Wax, 4 ℥.
Copal varnish, 1/2 ℥.
Red lead, 1/2 ℥.
Vermillion, 1 ʒ.
Melt together.
7.--_Green injection._
℞. Wax, 4 ℥.
Blue dross, 1/2 ℥.
Copal varnish, 1/2 ℥.
8.--_Blue injection._
To form this it is only necessary to add to the green injection, half a
drachm of powdered Prussian blue.”
The advantages of such preparations do not answer, in any degree, to
the promises of the title; the artificial preparations of M. Azoux are
much more preferable, since his cartons represent the form which the
anatomical pieces of Swan have lost by desiccation.
SECTION 1.--_Generalities of the operations which precede preservation._
Desiccation and immersion in liquids are the only means of preservation.
The choice of subjects which are to serve for these preparations,
says M. le Docteur Patissier, is not a matter of indifference.
Young subjects, and lean women, are preferable for the nerves and
bloodvessels; adults, and thin and dry old men, for the preparation of
bones which it is intended to articulate, and which it is desirable
to obtain in their greatest degree of development; individuals of an
athletic constitution for muscular preparations.
The most favourable time for the preparation and preservation of
anatomical subjects, is generally during a cold and dry winter, or
the ardent heat of summer; the more rapid is the evaporation of the
humidity of animal matters, the more sure is their preservation.
The method of preservation ought to be preceded by some other
operations, such as _dissection_, _maceration_, _injection_,
_ablution_, _corrosions_, _ligature of vessels_, _separation and
distention of parts_.
_a._ _Dissection._--It consists in stripping the part which it is
intended to preserve, of the tissues and organs which are foreign to
it: if the object be the preparation of muscles, for example, these
organs are left alone with their insertions in the bones, or rather,
the vessels, previously injected, preserve their relations with the
muscles and the bones. Nevertheless, in the dissection of the hard
parts, whether it is proposed to follow the branches of the vessels
and nerves which penetrate, or are distributed in their substance, or
whether it is desired to develop and render their organization more
apparent; it is less convenient to have recourse to instruments than
to chemical re-agents, which bring into view the parts which it is
desirable to study. When the object is the preparation of a bone only,
the operation consists of two parts, _excarnation_, and _etiolation_,
the details of which will be presented in the article upon bony tissues.
_b._ _Macerations and corrosions._--These operations are frequently
brought into use by the naturalist: water, acids, alkalies, volatile
oils, &c., serve to produce varied effects in the preparation of the
different tissues. The maceration of different portions of the skeleton
is produced by water. The employment of other liquids has for object,
in attacking several parts which they dissolve, to expose others which
it is desirable should be left bare.
Thus, in order to absorb the grease which exudes from the skeletons
of certain fish, or of bones, the maceration of which has not been
perfected, it is useful to steep the piece in a marly alluminous paste,
which must be alternatively put to dry and soften in the sun, in order
that the clay may absorb the fetid oils with which the bones are
impregnated.
In order to dissolve the grease with which certain parts are covered
some time after their preparation, as happens to some natural
skeletons, it is often necessary to steep the piece in an alkaline
liquor, or rather, to allow it to macerate for some weeks in a very
penetrating volatile oil. It is only by the aid of such processes
that we are able to follow encephalic nerves in many of the cetacea,
although these parts present in these animals extremely singular
dispositions.
It is with the same view that should be macerated either in water
elevated to a certain degree of temperature, or in acid liquors,
the hard tissues, in the interior of which it is proposed to denude
certain parts. Thus the nerves and vessels of the roots of the nails,
the horns, the skin, cannot be well exposed but by this process. The
canals, which traverse certain bones, cannot, as we have already shown,
be easily followed, unless the piece has remained for a longer or
shorter time in an acid liquor.
Macerations in alkaline and etherial liquors are still of great
assistance, as the researches so happily conceived and executed by
Bichat have proved.
Finally, corrosions are indispensable to the removal of the parenchyma
from injected preparations, when it is intended only to preserve the
interior network of vessels.
The following are the attentions which this operation exacts: The
injected part is consigned to a vessel of pure water for two or three
days, which is occasionally to be renewed, in order the better to
disgorge the vessels of any blood they may contain. It is afterwards to
be solidly fixed on a piece of wax at the bottom of a porcelain vase,
pierced with holes near the base, through which the liquor used to wash
them may flow off without deranging the vessels. This corrosive liquor
is the muriatic acid, or spirit of salt; the aquafortis of engravers,
or nitric acid, may be used for the same purpose.
The first time, the preparation is to remain two or three hours in
this acid, which is then drawn off and replaced by the same quantity
of water, which is allowed to flow on it in small streams. This water
is left for four or five days, according to the season, until the
water begins to be covered with a scum, and the preparation begins to
be cottony at its surface; the liquor is poured off a second time,
and the pot or vase is placed beneath the cock of a fountain, from
which escapes a delicate stream of water, which will carry off slowly
and without shocks, any detached parts; when it is perceived that the
washing carries off no more animal matter, the acid is poured into the
pot, of which the opening is to be reclosed with a stopper of glass
or porcelain, warmed and endued with wax. This operation is to be
repeated every four or eight days, until the tunics of the vessels are
altogether denuded, and the injected matter is seen throughout.[9]
[9] These details on maceration and corrosion, are extracted from a
work full of interest of Professor Dumeril: Essay on the means of
perfecting and extending the anatomical art.--(_Paris_, 1803.)
_c._ _Injections._--These are _evacuative_, _repletive_, _antiseptic_,
or _preservative_. The first have for object, as their name indicates,
to disembarrass the vessels or hollow organs, of the matters and fluids
which they contain; they consist of water, of acids very much reduced,
of diluted alcohol, &c. Thus it is serviceable to inject water or
alcohol into the bloodvessels to prepare them for the reception of the
repletive and preserving injections. The second are either definite or
temporary.
The substances employed in these injections are vehicles for colouring
matter. The nature of the vehicles determines that of the colours,
which ought to be as far as possible, analogous to those of the humors,
which the vessels contained during life.
As vehicles, those fluids which always retain their fluidity are rarely
employed, for parts thus injected cannot be dissected, and they are,
besides, apt to allow the colouring matters which they contain in
suspension, to be deposited.
Liquids saturated with glue or gelatine, made use of in ordinary
injections, have the inconvenience of not being equally solidifiable
at different degrees of temperature, or harden too rapidly by cooling;
they are made with the glue of commerce, either simple, or mixed with
gummy or saccharine matter; that commonly used, is called Flanders
glue, although it is manufactured in Paris, and that called mouth
glue, which only differs from the other in containing a little gum
or sugar. That which succeeds best, because it melts with the heat
of the hand, and which nevertheless coagulates at a temperature of
twenty-five or twenty-six degrees of Reaumer’s thermometer, which is
one of the highest points to which our atmosphere attains, is made of
the membranes of fishes, or icthyocolla. An ounce is to be melted in
a sand-bath, in double its weight of water, and mixed afterwards with
two ounces of alcohol, previously warmed. In these sorts of gelatinous
injections, there is much choice in the colouring matters. All those
that are ground like gum, and which are used in miniature painting, and
in painting “a la gouache,”[M] may be employed; they remain very well
suspended.
[M] Paintings where colours are employed diluted with water or
gum.--_Tr._
The sticks of carmine of Delafosse, and the carmine lacks of Hubert,
may then be used with advantage for the arteries; for the veins,
Prussian blue, ground in vinegar, and the white of zinc of Antheaume,
or that of oyster shells well porphyrized, for the colour of metallic
oxide is subject to change in animal matter; they are also subject to
the inconvenience of becoming precipitated by repose before the vehicle
cools, and thus obstruct the smaller vessels.
Liquors which can be made solid by the effect of certain re-actives,
offer, on this account, some advantage. It is thus, that it is
serviceable to soak for a day or two in a solution of nut-galls or
of tannin, those parts injected with gelatine, when it is intended to
preserve them dry. In partial injections of lymphatic vessels, and
particularly of the chyliferous, cow’s or goat’s milk, may be made use
of. When, after having tied the thoracic duct, injections of milk have
been made into all the vessels in which can be introduced the beak of a
glass syringe, or of the syringe used for injecting the lacrymal ducts,
pour on the surface of the injected parts strong vinegar, or a diluted
acid, which will coagulate the milk, so that the chyliferous vessels
will be found filled with a solid, white, and flexible.[10]
[10] There are some specimens in the museum of Natural History prepared
by this process.
The most common, the most solid, and the most convenient injections,
are made of fatty and resinous matter. Volatile oils, balsams, resins
dissolved in alcohol, fats, wax, and the most ordinary fixed oils,
are principally used. These different substances are combined, and
the compositions of them are varied according to the nature of the
injections, which it is desirable to prepare, and above all, according
to the manner which it is proposed to preserve them.
The nature and the preparation of the colouring matters, ought also to
vary according to the kind of fatty medium which is used.
The volatile oils being nearly equally penetrating, turpentine is
generally chosen, because it is cheaper. Nevertheless, for small
objects, the citron, or that of a species of lavender (aspie of the
shops) is preferred, on account of their odour, which are besides
not very expensive. When it is intended to inject only with one of
these oils, which makes a liquid matter extremely penetrating, after
having dissolved a colouring matter previously ground in a fixed oil,
the mixture is slightly heated. This liquor is generally employed to
render perceptible the small vessels of membranes, which are not to be
dissected, but well preserved in their integrity. If it is intended
to inject the large trunk which supplies these membranes towards the
end of the operation, it is necessary to inject a little essence of
varnish, charged with much resin, and before drying the piece, let
it soak a day or two in an aqueous solution of the deuto-chloride of
mercury, according to the process of Chaussier.
The matters with which the volatile oils are to be coloured, should be
previously ground with the greatest care. It is easy to procure those
which are prepared with nut oil, and which are sold in little bladders
to be employed upon palettes.
Colours, thus prepared and intimately amalgamated with fixed oils,
remain much better suspended; the heaviest oxides, even those of lead
and mercury, are not then subject to become deposited.
Resins, dissolved in spirits of wine, are also sold by the pint, all
prepared, under the name of varnish, and in general are not costly.
Those which the anatomist can turn from the ordinary arts to his own
profits, are employed principally in pieces which it is intended to
preserve dry. Perfect success attends the varnish, named in the shops
_fat_, _wood-red_, _a la copale_, and with some others which remain a
long time flexible.
These fluids are difficult to colour; it is necessary, for the first,
to grind the colouring matter with essence, and for the others with
alcohol; and to incorporate them afterwards with varnish after having
slightly heated them. The carmined lakes, thus suspended in fat
varnish, produce absolutely the effect of arterial blood; this colour
preserves very well, and with such like injections it is unnecessary to
colour the surface of the arteries.
The mixture of mutton fat or of suet, of white or yellow wax, of the
fixed oils of olives, nuts, or flax seed, are the ordinary matters
of injections, even for those destined for corrosions. The different
degrees of solidity or softness are determined by the calculated
proportions of wax and oil, and by the amalgam of resinous and
colouring matters.
In general, in this sort of injections it is advantageous to introduce
beforehand, a small quantity of volatile oil mixed with the fatty
matter which is to serve for filling the vessels; by this preliminary
process a liquid more fluid, more penetrating, higher coloured, and
susceptible of cooling more slowly, is driven before into the smaller
ramifications.
I could here transcribe several receipts proper to indicate the
proportion of fatty matters among themselves; but the season during
which the pieces are made, the nature of the ingredients employed
on them, will occasion the proportional quantities to vary, so that
a sketch only can be given for obtaining a matter which may be made
more solid or more fluid after having tried it by cooling some drops
separately. Nevertheless, here is one of those receipts:
℞. Of suet, 5 parts.
Burgundy pitch, 2 "
Oil of olives, or of nuts, 2 "
Of fluid turpentine and colouring
matter, dissolved in volatile oil, 1 "
This latter part should not be mixed until the liquor is well melted
and ready to be put into the syringe, as the heat will volatilize the
volatile oils, which will become disengaged in the form of gas, and
cause the mass to occupy a very great volume.
As a matter of injection, the dissolved gum elastic or caoutchouc
may be employed; it becomes gelatinized in losing a portion of its
menstruum by desiccation. After leaving this matter in a moist place,
and having well washed it, in order to clean it of the clayey matter
which generally impregnates it, it may be dissolved in volatile oils
by heating it in a sand bath, with a moderate fire in a matrass with a
long neck; adding by degrees, a sufficient quantity of oil to render
the mass very fluid, incorporating with it the colouring matters which
have been previously ground in an essential oil. The gum elastic may
also be dissolved in ether, but this process is too expensive; and as
a matter for injecting this liquor is not preferable to the other. The
elastic injections are only advantageous in the preparation of parts
which are not to be exposed to cutting instruments, and to which it
is desirable to preserve a certain degree of suppleness, as in the
injection of the cotyledons, or the placenta of women. This liquor, it
must be confessed, has the great inconvenience of retaining its odour
a long time, assuming its solid form with difficulty, and of rendering
the preparations pitchy, and rebellious to varnish, and becoming loaded
with dust.
There are certain organs which may be injected with solid matters,
in order to obtain, in relief, resisting, but coarse, the forms
of interior cavities. Such is the injection with the matter which
forms the stucco paste, or of fine plaster diluted with gelatinous
water, which gives to this salt a greater solidity when it takes its
consistency. This gross matter is employed with advantage to render
more solid the membranes of certain cavities, in the thickness of which
it is desired to search for the nerves. Pure wax does not present
the same advantage, because it exacts more heat, and contracts more
by cooling, although it is more applicable in case it is proposed to
corrode with acids all the fleshy or osseous parts, in order to become
acquainted with the real form of their interior capacity: in fine,
the fusible metallic mixture of Darcet is employed under different
circumstances, but it is not more useful.[11]
[11] M. Dumeril, work cited.
Preservative injections, which may also be applied to vessels and to
hollow organs, are composed of materials to which have been attributed
preservative properties to the tissues: such are the solutions of
mercurial salts, arsenical, ferruginous, &c., and different aromatic
and spirituous liquors.
_d._ _Ablutions_.--These vary according to the end proposed: acids;
these serve to give whiteness to some tissues and resistance to
others: alkaline; these clean the preparations, divesting them of
the mucilage and grease which they contain. In one word, the action
of aqueous liquids, of oily, alkaline, saline, acid, alcoholic,
is necessary before, as well as after dissection to preserve the
preparations.
When these preparations are left a longer or shorter time in water,
they are subjected to what is called a _degorgement_; the bath ought to
be renewed until it will no longer receive any colouring matter.
The removal of _grease_ is included under dissection, maceration, and
ablution.
_e._ _Ligature of the vessels._--This is made with a flat silk, or silk
very slightly twisted, during the dissection, or immediately after,
on the extremity of the vessel which contains the injection; it is
necessary in order to prevent the escape of the injected matter.
_f._ _Separation and distention of parts._--These offer the whole
surface of the prepared pieces to those agents of preservation which
ought to be applied to them; they sustain them, and preserve them from
being deformed. Besides, it is well known, that the means of separation
and distension ought to vary according to the form of the organs;
atmospheric air suffices for hollow and thin organs, the stomach, the
intestines, the bladder, &c. Under other circumstances, wool, hair
cotton, plaster, &c., serve better.
SECT. 2.--_Means of Preservation._
The means of preservation may be arranged under two principal heads,
as we have said, according as the anatomist intends to expose his
preparations to the open air, or to preserve them from insects and
render them more transparent by the aid of certain liquors, in which it
is intended to keep them continually.
_Preservation by desiccation._--When applied to soft parts is only
applicable to anatomy, properly so called, and to natural history; it
cannot be employed for specimens of pathological anatomy.
Desiccation is preceded by a more or less prolonged immersion,
according to the thickness of the organs in acid or saline solutions,
& c.; that which presents the greatest advantage for the nerves,
according to Dumeril, is diluted nitric acid. The salts commonly
employed present some inconveniences. Corrosive sublimate hardens
too much, and causes the parts to contract on each other; the triple
sulphate of alumine, (alum,) often chrystalizes in drying, which
produces in the interior of the piece, which ought to be pellucid,
saline vegetations, which not only elevate the organic lamina, often
rendering the surface tuberculous, but further deprive the part of the
transparency necessary to see the texture of it; the muriate of soda,
(white kitchen salt,) attracts the humidity of the air, and causes the
varnish to scale off, which can have no hold upon the preparation.
Diluted nitric acid, with which the parts are washed, does not expose
them to these inconveniences: the preparation preserves, it is true, a
certain degree of suppleness; it tarnishes a little, but is never humid.
The numerous means used for disposing the preparations to desiccation,
may be reported under four series:
Alcohol, where expense is no object, is preferable to all the others;
its affinity for water gives it the property of absorbing humidity from
anatomical pieces.
The deuto-chloride of mercury, the proto-nitrate of the same base,
the solutions of acetate of lead, and of the proto-nitrate, merit the
preference among metallic substances.
Marine salt and alum are nearly those alone among the earthy salts
which have been employed for this object. M. Breschet advises that,
according to the method followed by the tanners, the piece be permitted
to remain for several days in powdered sea salt, and to immerge it
afterwards in a strong solution of alum for fifteen days, when it is to
be withdrawn and dried.
In fine, tanning is still a preparatory method for desiccation.
_Desiccation._--Anatomical pieces may, says M. Doct. Patissier, be
dried in the open air, in a stove, in a vacuum, and by employing
substances very avaricious of water, and in a bath of sand, or of
absorbing powders; but desiccation by means of an oven is the best
process: the heat of the oven must be neither too weak nor too strong;
the most convenient temperature is that of 45° to 55° of centigrade.
When the parts have been dried by one of the processes just mentioned,
if they be abandoned to themselves, they would become injured in a
little time by humidity and insects. There remains, then, some care to
be taken before depositing them in a cabinet; they should be washed
in a liquid containing a preparation of arsenic, or of sublimate, or
rather by applying to them a varnish containing one or both of these
substances. We shall not reconsider here the compositions of varnishes,
having already given several formulæ for them when speaking of Swan’s
method, and we shall have occasion to refer to them again when passing
in review the different methods of preparing objects of natural history.
_Preservation in liquids._--Anatomical parts are also preserved, and
more advantageously, in liquids. We shall now consider the acids, or
acidulated waters, alkalies, salts, oils, spirituous or alcoholic
liquors; expose their advantages under certain circumstances, their
inconveniences under others.
When acids are employed for preserving anatomical parts in their
natural state of suppleness, caution must be used to dilute them,
with a sufficient quantity of water, so that they may not corrode or
harden the parts. In general, it is advantageous to allow them to
remain for the first few days, in a very weak acid, and not place them
in the prepared liquor, until they have ceased to make any deposit.
The objections against muriatic acid are, that it renders the surface
of the parts gelatinous, gluey, and transparent; of nitric acid, to
tarnish and contract them; of sulphuric acid, to bleach them. All
these acids decompose the parts when they are not sufficiently diluted
with water; they allow the liquor to putrefy or to freeze, and break
the vessel when they are too weak. The proportions are indicated by
experience, and depend upon the nature of the part which it is intended
to preserve. It is those parts in particular which are loaded with fat,
that are best preserved in acid liquors.
In general, little use is made of liquors which hold alkalies in
solution: the carbonates of commerce are preferable; and these are used
with advantage, when it is necessary to keep for several days, before
dissection, animal parts in which corruption has already commenced.
Those salts derived from the combination of acids and earths, the
alkalies or metals, may be employed like the acids diluted with
water. They are not subject to the same objections. The nitrate of
potash, the muriate of ammonia, those of lime, or of soda, are very
proper for preserving pieces of myology; they appear even to reclaim
the red colour of the muscles, when these solutions are strongly
saturated; but, then, they are liable, some of them, to liquify,
others, to effervesce or to chrystalize upon the sides of the jars,
and even on the surface of the parts themselves, which is a very great
inconvenience when it is wished to expose the parts to view.
The solution of the triple sulphate of alumine, (alum of commerce)
is employed with the same advantages; it must be confessed, however,
that they are more proper to preserve membranous parts which have been
previously allowed to macerate a long time. In general, this liquor
discolours the parts, and deposits at length on the sides of the jar
and the surface of the piece which it bleaches, the white earthy
matter with which it is charged; this is a great objection, and exacts
great care when the atmosphere freezes suddenly.
Chaussier has latterly proposed the solution of the deuto-chloride
of mercury, in distilled water. This liquor is very useful, but it
bleaches the surface of the parts, particularly the muscles; it
hardens, and attacks the instruments when new researches are attempted,
upon parts already prepared. This discovery, however, is very valuable
to obtain the mummification of certain parts, which it is intended to
preserve in the open air. In order to obtain a solution always equally
saturated, Chaussier,[12] has proposed to keep at the bottom of the
liquor two or three knots of fine linen enclosing a certain quantity of
this metallic salt, in order that the saturation may always be complete.
[12] See Bulletin des Sciences, by the Philomatic Society, Vol. 3, 6th
year, No. 3.
In general, we repeat, these preservative liquors are attended with the
great inconvenience of leaving suspended, after frosts, the albuminous
matters which the cooling has caused to precipitate; so that the fluid
of the vessel which contains the preparation becomes clouded, and no
longer permits the object so be clearly seen. Besides, the liquor
freezes, and breaks the jar, when the temperature is very low.
The volatile oils, from whatever vegetable they may have been
extracted, are very proper for the preservation of anatomical objects;
they lose at length, it is true, their transparency; they thicken,
precipitate to the bottom of the vessel, the animal fluids which
exude from the object, which exposes them to corruption. But all these
changes are sensible to the eye, and the fault is easily repaired
when perceived in time to renew the liquor, which may be afterwards
re-distilled.
It is never useful to employ these liquids for the preservation
of objects loaded with fat, for they dissolve these at length and
penetrate them entirely, changing their form and colour.
Volatile oils, and particularly turpentine, which is the best, are
employed to preserve with the greatest success certain injections, the
vehicles of which would be dissolved in alcohol, and all the parts
whose vessels have been injected with coloured gelatine; finally,
these oils are used in all cases where it is desirable to preserve the
transparency of certain membranes, which have been previously dried.
Alcoholic liquors are most generally used for the preservation of
animal substances, if they are more costly, they are liable to fewer
objections. Brandy, rum, tafea, are coloured by a resinous substance,
which clouds their transparency, and which is liable to be deposited.
The alcohol of cherries, of grain, of cider, or of wine, is preferred
at present, which can be procured well rectified and transparent, and
which may be afterwards weakened with distilled water, so as to obtain
alcohol very limpid, marking from 22° to 30° of Baume’s areometer.
Some years since, alcohol was still employed, in which was dissolved
certain transparent resins; such as camphor, but it has since been
ascertained, that animal substances which have remained in this
liquor, contract such a disagreeable and nauseous odour, that it
becomes very painful to keep them long uncovered for examination,
consequently, pure alcohol is preferred.
Nevertheless, when it is desirable to preserve the preparations of
the nerves, it is better to put a few drops of muriatic acid into the
jar along with the spirits of wine: this mixture bleaches and renders
more visible the nervous fibres, on which the acid appears to act more
specially. The yellow tinge, which the parts sometimes assume in the
end, may sometimes be removed by pouring a small quantity of muriatic
acid into the jar which contains them: this precaution occasionally
gives a new aspect to the parts.
We have chosen this passage of M. Dumeril’s pamphlet, because it
gives with sufficient accuracy all the liquids employed by preparors,
and because it indicates a part of the inconveniences which we have experienced from them. |
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