The Hand Phrenologically Considered 3

The Hand Phrenologically Considered 3

CHAPTER III.

 

“Bestimmt Die Gestalt die Lebensweise des Thieres

Und die Weise zu leben sie wirkt auf alle Gestalten

Mächtig Zurück.”—GÖTHE, _Metamorphose der Thiere_.

 

CORRESPONDENCE BETWEEN FORMS AND HABITS OF ANIMALS.

 

 

The most simple observation renders at once apparent a correspondence

between the external form of animals, the general direction of their

tendencies, and their habits.

 

Let us examine this question at somewhat greater length. From the

age of Aristotle to the present time, zoologists have arranged

the almost countless tribes of animals into a number of groups or

divisions, more or less related in general habits and structure. All

the classifications which have been hitherto proposed may be referred

to one or the other of two general principles. Either the colour of

the blood (Aristotle), the conformation of the heart (Hunter), the

arrangement of the nervous system (Owen), or some other peculiarity of

_internal_ structure, has been selected as the basis of arrangement;

or the animal creation has been grouped according to certain definite

circumstances connected with outward form and configuration. As

regards their internal organisation, the variations in the structure

and arrangement of the nervous system affords by far the best means

of classifying animals, and the whole animal world has accordingly

been divided into five primary divisions. We have already endeavoured

to prove that the manifestations of mind are only made known to us

through the medium of corporeal organs, whatever may be the nature of

its essence. By the state of the nervous system volition is modified or

controlled, the operation of the senses accelerated or retarded, the

muscular movements rendered feeble and uncertain, or strong, vigorous,

and energetic; in fine, the chief manifestations of life, thought,

volition, and independent motion, are all regulated by the condition

and structure of the central nervine masses.

 

 

APPENDAGES TO THE TRUNK A KEY TO THE ENTIRE ORGANISATION AND HABITS OF

ANIMALS.

 

The appendages to the trunk, like the arrangement of the nervous

system, furnish also a leading peculiarity of structure, and they may

be selected as the basis of a classification founded upon outward form.

For the most part, destined either for the purposes of locomotion,

or to assist in the procuring of food, they must of necessity be in

perfect accordance with the nervous and nutritive systems. Hence

the capacities, powers, and general habits of an animal, must be in

correspondence with this part of its organisation; so that when we

are acquainted with the form and arrangement of the extremities of an

animal, a key is thereby afforded to its entire organisation. Both its

external configuration, its mode of life, and its internal structure,

must harmonise, and be in accordance with the arrangement of the

extremities. Its breathing and vascular apparatus, its nutritive and

generative systems, are thus all indicated to us; and from a knowledge

of one particular we may safely and surely predicate the nature of the

rest.

 

_Annelida._—Thus in the worms (_Annelida_), creatures exhibiting but

few of the higher manifestations of life, we find the appendages

to the trunk in their simplest form,—that of fine, minute bristles

attached to the several rings or segments of the body. In the sea-mouse

(_Aphrodita_), their bristles attain a somewhat higher developement,

each of them being connected with a distinct elevation, or mammillary

process, with which it is, as it were, articulated.

 

_Myriapoda._—In the Centipedes, the first evidence of a well-formed

extremity makes its appearance in the form of numerous articulated legs

terminated by simple points. These legs, rudimentary in the lowest

species (_Iulidæ_), in harmony with their retiring habits and vegetable

diet, are divided into distinct joints, and provided with proper

muscles, in the strong and carnivorous varieties (_Scolopendridæ_). In

these latter animals, the ventral nervous ganglia are also increased

in size, in a ratio proportioned to the higher and more complex

structure of the appendages to the trunk.

 

_Insects._—In insects, creatures distinguished by so many and such

admirable instincts, and endowed with such active powers of locomotion,

the appendages to the body, both legs and wings, are perfectly and

beautifully formed. The former, six in number, are attached to the

three first thoracic segments of the body, composed of distinct

articulations, connected by ligaments and muscles, and furnished

with a series of minute breathing tubes, or tracheal ramifications,

extending throughout their entire substance. The latter—the wings—vary

much in their number, form, and arrangement; and it is upon characters

furnished by them that the nearest approximation to a perfect

classification of insects—that of Burmeister—is based. Thus, the legs

are typical of the class, the wings characterise the orders.

 

_Arachnida._—In the spider tribe (_Arachnida_) the legs, in their

general structure, resemble those of insects; but they are eight in

number, and, in addition to them, these creatures are provided with

remarkable claw-like appendages to their jaws—mere organs of feeling

in the mites, but strong and powerful instruments of prehension in the

scorpion tribe.

 

_Crustacea._—The crab and lobster tribe (_Crustaceans_) are likewise

accurately characterised by the appendages to the trunk, the number and

disposition of these parts having been employed by Milne Edwards for

the purpose of dividing these creatures into a number of orders.

 

_Mollusca._—Among the mollusks, the classes are nearly all named from

the peculiarities in form or the position of the feet. We have the

barnacles (_Cirrhopoda_), animals with six pair of articulated flexible

arms, composed of a series of small pieces studded with minute hairs,

and which form, when they are extended, a species of net by means of

which the animal catches its prey. The _Branchiopoda_—creatures such

as the _Terebratula_—with two long fleshy arms placed near the mouth,

which are hollow, muscular, and disposed in spiral folds. We have the

_Tunicata_, such as _Ascidians_ and the _Conchifera_, as the oyster and

mussel, beings which are destitute of members, and all but incapable

of locomotion. The _Gasteropoda_, of which the slug and snail afford

familiar examples, and that are furnished with a locomotive apparatus

peculiar to the whole class, and termed the foot or ventral disc. The

_Pteropoda_, nearly allied to the _Gasteropoda_ in their internal

organisation, but differing from them in the possession of two broad

fleshy expansions, resembling fins, which are attached to the side of

the neck, and are well adapted for swimming. And, lastly, we have the

_Cephalopoda_, such as the nautilus and cuttle-fish, creatures with

numerous strong muscular arms attached around the head, and in some

species provided with sucking discs, by means of which they are enabled

successfully to attack and capture the strongest and most active prey.

In all these instances we clearly see that the appendages characterise

the class, and that, from an acquaintance with their number and

arrangement, a naturalist could readily come to a conclusion as to the

affinities, structure, and general habits of any animal in the series.

 

_Fishes._—The fishes are divided into two great natural orders—those

furnished with a bony skeleton and those in which the framework of the

body is cartilaginous. The former division are distinguished by the

possession of a swimming bladder, and by the nearly equal developement

of the parts corresponding to the extremities—the pectoral and ventral

fins. The pectoral fins, situated immediately behind the head, are

present in all the osseous fishes, traces of them being found even

where they might be supposed to be entirely wanting, as in the eel;

they do not, however, attain any very considerable size, rarely

equalling, and never surpassing, the magnitude of the ventral fins.

In the cartilaginous fishes, on the contrary, not only in those which

ordinarily remain quiet at the bottom of the water, as the skate, the

sole, the flounder, and other flat fishes, but even in the active and

voracious sharks we find no swimming-bladder. In these cases, its

place is supplied and its duty performed by the enormously developed

anterior member or pectoral fin, which greatly surpasses the ventral

fin in size; and it is by means of the active movements of this large

hand that these creatures raise themselves from the bottom of the water

to the surface.

 

_Reptiles._—In the class of reptiles the characters afforded by

the form of the extremities are not less important. Of the four

orders into which this class is divided, one—that of the serpents

(_Ophidia_)—is altogether destitute of members, with the exception of

the rudimentary traces of extremities met with in some few species

(_Anguis_, _Bimanes_, and _Seps_). In another order, that of amphibious

animals (_Batrachia_), as the frogs, toads, &c., the extremities

are still typical of certain peculiarities of organisation. Some of

these creatures may be said to remain in an imperfectly developed or

embryonic condition during their whole existence. Instead of breathing

in adult life by means of lungs, as do the more perfectly organised

of the _batrachia_, they retain throughout existence that peculiar

structure of the respiratory apparatus—the branchial tufts—which

in the latter are present but in the embryo condition. In those of

the amphibious animals which breathe by means of permanent branchia

(_Perenni-branchiata_), such as the _Lepidosiren_ and the _Proteus_,

the extremities are either mere filamentary appendages, or at most

but very imperfectly-formed organs, and always typical of their

comparatively inferior organisation; while, in the higher species,

that is, those provided with lungs, and losing their branchiæ in the

adult state (_Caduci-branchiata_), as the frog, the salamander, &c.,

the extremities are well formed and perfectly developed. The third

order of reptiles—that of the lizard tribe (_Sauria_)—is made up of

members very dissimilar both in their appearance and general habits. In

the aquatic crocodiles the toes are connected by means of a membrane;

like ducks and other aquatic animals, these creatures are web-footed.

The alligator, so nearly allied to the crocodile in structure and

habits, with the exception that it is more terrestrial in its nature,

is furnished with a foot the toes of which are only webbed in half

their length, the other half being free and unconnected by membrane,

their amphibious mode of life being indicated by their foot. If we

compare the foot of these creatures with that of the true lizards,

the difference of structure will be found to be considerable. The

foot of the true lizard is provided with five toes to both the fore

and hind members, while attached to the hinder members of crocodiles

and alligators we find but four toes. The toes of the lizard are not

connected by a membrane, but are separate, and armed with nails,

for these creatures live on land, and have need of well-constructed

locomotive organs to enable them to catch their active prey. Among

lizards, that remarkable animal the chameleon, that is provided with

a particular structure of the skin, whereby its change of colour

is effected, is distinguished by the possession of a member, the

structure of which is not less peculiar. The toes are arranged in

two packets, which are capable of being brought into opposition—a

structure admirably adapted to the mode of life of the animal—the

climbing of trees and shrubs in pursuit of insects. The ichthyosaurus

and plesiosaurus, creatures of the lizard tribe which have now become

extinct, are both characterised by the form of their extremities.

The former has four members like paddles, each composed of nearly a

hundred small bones of an irregular polygonal shape and arranged in a

pavement-like form. The latter has also four paddle-shaped extremities,

but the number of bones of which each is composed is much less than in

the ichthyosaurus—not above fifty, the pieces being at the same time of

a different shape, and not arranged in a tessellated form.

 

_Birds._—Among birds the foot is a most important organ, serving

at once for support, prehension, and locomotion. Its modifications

are accordingly very numerous, and ornithologists have employed the

characters presented by it as a basis of classification. Scopoli, in

his Introduction to Natural History (1777), proposed a systematic

distribution of birds into two divisions founded upon the form of the

scales covering the foot; thus, some are furnished with scales, small

and polygonal (_Retepedes_), while others (_Scutipedes_) have the

legs covered in front with unequal semicircular plates. So, again,

in the division of birds proposed by Nitzsch, viz. into the aerial,

terrestrial, and aquatic, the foot will at once serve to indicate the

different orders. We will proceed to examine the special characters

afforded by the foot of birds in each of the groups or orders, adopting

the classification of Kirby, one of the most recent.