NERVOUS SYSTEM. (NERVOUS CENTRES. ABNORMAL ANATOMY.) 719 



indicating u feeble developement of the insula 

 ofReil. 



A few fissures and imperfectly developed 

 convolutions were found upon the inferior sur- 

 face of the middle lobe, as well as upon the 

 lateral and inferior surfaces of the anterior lobe. 

 The olfactory fissures were perfect but very 

 small; the olfactory nerves appeared natural. 

 The optic nerves were natural but small. 

 The tuber cinereum was large and well 

 developed. 



The corpora mamillaria appeared to be fused 

 together along the median line. 



The pons Varolii very narrow from before 

 backwards ; the groove which passes along its 

 middle was imperfect. 



The corpus striatum was exceedingly small, 

 and the groove between it and the optic thala- 

 mus was greatly increased in size. The tsenia 

 semicircularis was large. 



The convolution of the corpus callosum was 

 very imperfectly developed. The hippocampus 

 major was very small, and there could scarcely 

 be said to be any trace of the hippocampus minor. 

 The fornix was well developed, as was also 

 the corpus callosum. The longitudinal tracts 

 on the surface of the corpus callosum were also 

 well developed. 



The pineal gland was large and situate very 

 far forwards, corresponding very nearly to the 

 middle of the optic thalamus. The quadri- 

 geminal tubercles seemed imperfectly deve- 

 loped, and the distinction between them was 

 badly marked. 



The optic tract was small, but natural in its 

 connections. The cerebellum was well deve- 

 loped : its lamina seemed natural. The lateral 

 ventricles were large and rather dilated. The 

 entire brain, after having lain in spirits for some 

 days, weighed 1 Ib. 4J oz. avoirdupois. 



In some instances the hemispheres of the 

 brain are fused together, there being little or 

 no trace of a longitudinal fissure to separate 

 them. This condition occurs generally in the 

 Cyclopic monsters, or in monsters in which 

 there is a total absence of the organs of vision. 

 Where there is this singleness of brain there is 

 also sometimes a fusion of the corpora striata 

 and optic thalami of opposite sides together. 



A total absence of all the transverse com- 

 missures of the brain constitutes, as Elokilansky 

 observes, the opposite condition to that just 

 detailed. 



Idiotcy results from any change which im- 

 pairs to a material extent the structure of the 

 hemispheres of the brain and of the fibres by 

 which they are connected to each other, as well 

 as to the other parts of the encephalon. All the 

 recorded instances of dissections of the brains 

 of idiots shew that the evil consists, in such an 

 impairment of the hemispheres and their con- 

 voluted surface as must, have materially pre- 

 vented their proper action. This may have 

 begun in intra-uterine life or in infancy. The 

 brain of infants at birth is far from being fully 

 formed, and that part of it which is imperfectly 

 developed is that upon which depends the mani- 

 festation of mental actions, namely, the hemi- 

 .spheres of the brain and of the cerebellum; the 



other parts, which are mostly concerned in phy- 

 sical nervous actions, are sufficiently perfect, 

 being, however, generally small from the in- 

 fluence of the deficiency of the hemispheres. 



Hypertrophy of the brain would occasion 

 idiotcy, just as well as atrophy or imperfect 

 developement of that organ (ugenesie). Well- 

 marked cases of idiotcy resulting from the 

 former cause are, however, as far as I know, yet 

 wanting in medical records. 



When there is a deficiency in any part of the 

 cranial wall, a protrusion of a greater or less 

 portion of the brain takes place this consti- 

 tutes hernia cerebri or encephalocele. It is in 

 point of size proportionate to the size of the 

 opening in the cranium. The tumour is co- 

 vered externally by the common integuments, 

 and the displaced portion of the brain pushes 

 before it the dura mater and the other mem- 

 branes of the brain. 



The most frequent situation for hernia cerebri 

 is in the occipital region of the head near the 

 middle line, and next in point of frequency 

 somewhere on the median line, where the bones 

 of opposite sides remain for so long a time 

 disunited : near the great fontanelle is a fre- 

 quent site of a protrusion ; sometimes it takes 

 place on the side of the skull in the temporal 

 region, or at the root of the nose. Such cases, 

 however, are rare. 



2. Morbid conditions of the brain. Hy- 

 pertrophy. The examples of hypertrophy 

 of the brain which are on record are not 

 numerous, and it is difficult to attribute the 

 appearances, which are said to indicate this 

 condition, to a mere increase in the nutrition 

 of the organ- Adopting the term, however, in 

 deference to the high authorities who have ap- 

 plied it, it may be stated that the anatomical 

 characters of a hypertrophic brain are as fol- 

 lows : 



The brain appears too large for the skull ; 

 on the removal of the calvaria the dura mater 

 seems perfectly tense and filled by the brain ; 

 it appears thinner and more transparent than is 

 quite normal, and there is no trace of fluid in 

 the subarachnoid space. 



The hemispheres are large, and their convo- 

 lutions lie closely packed beside each other, 

 and flattened. The ventricles of the brain are 

 small, exhibiting the same condition as the 

 fissures between the convolutions. The surface 

 of the arachnoid as well as of the intra-ventri- 

 cular eminences is dry or nearly so. 



The substance of the brain is universally 

 firm, and cuts somewhat like cartilage ; it is 

 exsangueous, the principal accumulation of 

 blood being in the pia mater. The colour of 

 the grey matter becomes so changed as to be 

 scarcely different from the white. 



It is as yet uncertain what is the precise 

 change which the brain undergoes in this con- 

 dition. We know that there is an increase of 

 substance, but whether that be an increase in 

 the normal size of the fibres and vesicles of the 

 two varieties of nervous matter which are found 

 in the brain, or in their number, or whether it 

 be a deposition of new material, with or with- 

 out increase in the size or number of the ele- 



