and impressibility of organization which take the place, to a certain extent, of the purely intellectual faculties.

This was the case, in a marked degree, with a pair of dwarfed and idiotic Central American children, who were exhibited a few years ago in various parts of the United States, under the name of the "Aztec children." They were a boy and a girl, aged respectively about seven and five years. The boy was 2 feet 9 inches high, and weighed a little over 20 pounds. The girl was 2 feet 5 inches high, and weighed 17 pounds. Their bodies were tolerably well proportioned, but the cranial cavities, as shown by the accompanying portraits, were extremely small.

The antero-posterior diameter of the boy's head was only 41 inches, the transverse diameter less than 4 inches. The anteroposterior diameter of the girl's head was 4 inches, the transverse diameter only 3 inches. The habits of these children, so far as regards feeding and taking care of themselves, were those of children two or three years of age. They were incapable of learning to talk, and could only repeat a few isolated words. Notwithstanding, however, the extremely limited range of their intellectual powers, these children were remarkably vivacious and excitable. While awake they were in almost constant motion, and any new object or toy presented to them immediately attracted their attention, and evidently awakened a lively curiosity. They were accordingly easily influenced by proper management, and understood readily the meaning of those who addressed them, so far as this meaning could be conveyed by gesticulation and the tones of the voice. Their expression and general appearance, though decidedly idiotic, were not at all disagreeable or repulsive; and they were

much less troublesome to the persons who had them in charge than is often the case with idiots possessing a larger cerebral development.

It may also be observed that the purely intellectual or reasoning powers are not the only element in the mental superiority of certain races or of particular individuals over their associates. There is also a certain rapidity of perception and strength of will which may sometimes overbalance greater intellectual acquirements and more cultivated reasoning powers. These, however, are differ ent faculties from the latter; and occupy, as we shall hereafter see, different parts of the encephalon.

A very remarkable physiological doctrine, dependent partly on the foregoing facts, was brought forward some years ago by Gall and Spurzheim, under the name of Phrenology. These observers recognized the fact that the intellectual powers are undoubtedly seated in the brain, and that the development of the brain is, as a general rule, in correspondence with the activity of these powers. They noticed also that in other parts of the nervous system, different functions occupy different situations; and regarding the mind as made up of many distinct mental faculties, they conceived the idea that these different faculties might be seated in different parts of the cerebral mass. If so, each separate portion of the brain would undoubtedly be more or less developed in proportion to the activity of the mental trait or faculty residing in it. The shape of the head would then vary in different individuals, in accordance with their mental peculiarities; and the character and endowments of the individual might therefore be estimated from an examination of the elevations and depressions on the surface of the cranium.

Accordingly, the authors of this doctrine endeavored, by examining the heads of various individuals whose character was already known, to ascertain the location of the different mental faculties. In this manner they finally succeeded, as they supposed, in accomplishing their object; after which they prepared a chart, in which the surface of the cranium was mapped out into some thirty or forty different regions, corresponding with as many different mental traits or faculties. With the assistance of this chart it was thought that phrenology might be practised as an art; and that, by one skilled in its application, the character of a stranger might be discovered by simply examining the external conformation of his head.

We shall not expend much time in discussing the claims of phrenology to rank as a science or an art, since we believe that it has of late years been almost wholly discarded by scientific men, owing

to the very evident deficiencies of the basis upon which it was founded. Passing over, therefore, many minor details, we will merely point out, as matters of physiological interest, the principal defects which must always prevent the establishment of phrenology as a science, and its application as an art.

First, though we have no reason for denying that different parts of the brain may be occupied by different intellectual faculties, there is no direct evidence which would show this to be the case. Phrenologists include, in those parts of the brain which they employ for examination, both the cerebrum and cerebellum; and they justly regard the external parts of these bodies, viz., the layer of gray matter which occupies their surface, as the ganglionic portion in which must reside more especially the nervous functions which they possess. But this layer of gray matter, in each principal portion of the brain, is continuous throughout. There is no anatomical division or limit between its different parts, as there are between the different ganglia in other portions of the nervous system; and consequently such divisions of the cerebrum and cerebellum must be altogether arbitrary in character, and not dependent on any anatomical basis.

Secondly, the only means of ascertaining the location of the different mental traits, supposing them to occupy different parts of the brain, would be that adopted by Gall and Spurzheim, viz., to make an accurate comparison, in a sufficient number of cases, of the form of the head in individuals of known character. But the practical difficulty of accomplishing this is very great. It requires a long acquaintance and close observation to learn accurately the character of a single person; and it is in this kind of observation, more than in any other, that we are proverbially liable to mistakes. It is extremely improbable, therefore, that either Gall or Spurzheim could, in a single lifetime, have accomplished this comparison in so many instances as to furnish a reliable basis for the construction of a phrenological chart.

A still more serious practical difficulty, however, is the following. The different intellectual faculties being supposed to reside in the layer of gray substance constituting the surfaces of the cerebrum and cerebellum, they must of course be distributed throughout this layer, wherever it exists. Gall and Spurzheim located all the mental faculties in those parts of the brain which are accessible to external exploration. An examination of different sections of the brain. will show, however, that the greater portion of the gray substance is so placed, that its quantity cannot be estimated by an external

Fig. 140.

examination through the skull. The only portions which are exposed to such an examination are the upper and lateral portions of the convexities of the hemispheres, together with the posterior edge and part of the under surface of the cerebellum. (Fig. 140.) A very extensive portion of the cerebral surface, however, remains concealed in such a manner that it cannot possibly be subjected to examination, viz., the entire base of the brain, with the under surface of the anterior and middle lobes (1,2); the upper surface of the cerebellum (3) and the inferior surface of the posterior lobe of the cerebrum which covers it (4); that portion of the cerebellum situated above the medulla oblongata (5); and the two opposite convoluted surfaces in the fissure of Sylvius (6, 7), where the ante

Diagram of the BRAIN IN SITU, showing those portions which are ex

rior and middle lobes of the cerebrum posed to examination.

lie in contact with each other. The whole extent, also, of the cerebral surfaces which are opposed to each other in the great longitudinal fissure (Fig. 141), throughout its

Fig. 141.

entire length, are equally protected by their position, and concealed from external examination. The whole of the convoluted surface of the brain must, however, be regarded as of equal importance in the distribution of the mental qualities; and yet it is evident that not more than one-third or onequarter of this surface is so placed that it can be examined by external manipulation. It must furthermore be recollected that the gray matter of the cerebrum and cerebellum is everywhere convoluted, and that the showing depth of great longiconvolutions penetrate to various depths

Transverse section of BRAIN,

tudinal fissure, at a.

in the substance of the brain. Even if we were able to feel, therefore, the external surface of the brain itself, it would not be the entire convolutions, but only their superficial edges, that we should really be able to examine. And yet the amount of gray matter contained in a given space depends quite as much upon the depth to which the convolutions penetrate, as upon the prominence of their edges.

While phrenology, therefore, is partially founded upon acknowledged physiological facts, there are yet essential deficiencies in its scientific basis, as well as insurmountable difficulties in the way of its practical application.

CEREBELLUM.

The cerebellum is the second ganglion of the encephalon, in respect of size. If it be examined, moreover, in regard to the form and disposition of its convolutions, it will be seen that these are much more complicated and more numerous than in the cerebrum, and penetrate much deeper into its substance. Though the cerebellum therefore is smaller, as a whole, than the cerebrum, it contains, in proportion to its size, a much larger quantity of gray matter.

In examining the comparative development of the brain, also, in different classes and species of animals, we find that the cerebellum nearly always keeps pace, in this respect, with the cerebrum. These facts would lead us to regard it as a ganglion hardly secondary in importance to the cerebrum itself.

Physiologists, however, have thus far failed to demonstrate the nature of its function with the same degree of precision as that of many other parts of the brain. The opinion of Gall, which located in the cerebellum the sexual impulse and instincts, is at the present day generally abandoned; for the reason that it has not been found to be sufficiently supported by anatomical and experimental facts, many of which are indeed directly opposed to it. The opinion which has of late years been received with the most favor is that first advocated by Flourens, which attributes to the cerebellum the power of associating or "co-ordinating" the different voluntary

movements.

It is evident, indeed, that such a power does actually reside in some part of the nervous system. No movements are effected by the independent contraction of single muscles; but always by several muscles acting in harmony with each other. The number and complication of these associated movements vary in different classes of animals. In fish, for example, progression is accomplished in the simplest possible manner, viz., by the lateral flexion and extension of the vertebral column. In serpents it is much the same. In frogs, lizards, and turtles, on the other hand, the four jointed extremities come into play, and the movements are some