Average. Highest. Lowest.
Stallions.. 61 .. 65 .. 56 Alares.... 61 66 .. 58 Geldings.. 70 .. 76 .. 64 Thus the remarkable result is obtained, that castration tends to augment the weight of the cerebellum, and not to reduce it, as Gall and his followers atfirm.
What is further very remarkable in these re searches is that the cerebrum in geldings is on the average less in weight than that in stallions; and the fact gives great confirmation to the results of weighing the cerebella, rendering it in the highest degree improbable that the excess of weight in the cerebellum was accidental.
The general expression of the facts obtained by Leuret is this, that in horses, mutilated as regards the principal generative organs, the cerebellum is heavier than in horses and mares not mutilated in the generative organ ; and he coinpared twenty-one of the former with twenty two of the latter.
Compare these observations with those above quoted from Gall by AIr. Noble, a most ardent phrenologist, and I think most unprejudiced persons will admit that in the number of ob servations, in the exactness with which those observations were conducted, and in their free dom from sources of fallacy, the researches of M. Lenret have greatly the advantage over those upon which Gall rests his conclusion.
Yet Mr. Noble, while he unhesitatingly accepts the few and very feeble instances quoted and adopted by Gall, is at great pains to depreciate these observations of Leuret; first, because they are not sufficiently numerous; secondly, because Alr. Parchappe found that, in comparing the cerebra and cerebella of a certain number of mad men and women with those of sane men and women, a very slight advantage existed in favour of the former; and, thirdly, because the author of the observations is an opponent of phrenology.
I must say, however, upon this point, that, while I do not reckon myself arnong the op ponents to phrenology, but rather among those who are anxiously looking for and desirous of promoting a truly scientific phrenology,* I can not but regard the facts brought forward by M. Leuret as of the greatest interest and im portance, arid not to be affected by any such arguments as those of Air. Noble; nor are they to be met at all, save by similar weighings, in the same, or still better, in double the number of animals.
The last point to be noticed with regard to Gall's theory of the office of the cerebellum is that it certainly derives no support from patho logical observations. The few cases quoted by Gall, in which the injury in the neighbour hood of the cerebellum seemed to affect sexual instinct are far from being conclusive, for they might apply equally, if it were assumed that the seat of the instinct were in the posterior lobes of the cerebrum, in the medulla ob longata, or in the spinal cord. Indeed Baron
Larrey's second case is much more favourable to the localization of the genemtive impulse in the cehtre of emotions, than in the cerebellum. For the latter organ was free from disease, whilst the medulla oblongata was indurated. And, further, the assumed connection between the generative instinct and the cerebellum, from the occasional existence of an abnormal erection of the penis, is not justified by the facts. This symptom is far from being constant in cerebellar disease—indeed it occurs in but a very sniall number of cases—and, as a syrnptom pointing to lesion of a particular portion of the cerebro spinal axis, it is much more indicative of disease of the medulla oblongata or of the cervical portion of the spinal cord.
Office of the cerebral convolutions.—The great sheet of vesicular matter which forms the cortex of the human brain, is of such vast extent that it is forced to assume the convo luted form in order to its being packed within the ordinary compass of the cranium. A little consideration will shew that the convoluted form can be regarded no otherwise than as a convenient mode of packing, and that the number and depth of the convolutions are the best indications of the superficial extent of this expanse of vesicular matter. In certain cases a slow and gradual accumulation of water within the ventricles of the brain, causing a corresponding enlargement of the cranium, expands the matter of the cerebral hemispheres, by which the ventricles are enclosed, and the convolutions become unfolded. We thus ob tain a distinct demonstration of the true arrange ment of this part of the hemisphere, which must be regarded as a nervous centre, con sisting of a vast mass of the potential vesi cular matter freely supplied with bloodvessels from a vascular surface on its exterior (the pia mater), and giving rise to an infinite multitude of nerve-fibres, which pass from its internal surface to the corpora striata and optic thalami, the centres of volition and sensation. The name which Mr. Solly has given to this ex panse of nervous matter, hemispherical gan glion, is very expressive, not only of its true character as a centre of nervous power, but likewise of the unity of the organ on each side, consisting as it does of an uninterrupted layer of vesicular matter with its emerging or im merging fibres, and not of a great number of different organs, as the term convolutions would imply.