ON THE BRAINS OF TWO IDIOTS OF EUROPEAN DESCENT. 
547 
well developed in both brains ; the soft commissure is very large in both. Of the longi- 
tudinal commissures the fornix is proportionally large ; the tsenia semicircularis and 
striae longitudinales, very distinct in the boy, are also easily traceable in the woman. 
The septum lucidum and middle ventricle are small in both the idiots’ brains, the interval 
between the fornix and the corpus callosum being narrow. The lateral ventricles in 
both brains, in accordance with the restricted development of the frontal and occipital 
regions, are comparatively short and wide cavities. The general direction of the body 
of the ventricle is not parallel with the median line, but divergent outwards and back- 
wards — a condition owing evidently to the optic" thalamus being proportionally large, or 
at any rate well developed, whereas the corpus striatum is relatively very small, the 
eminence formed by it within the ventricle being short and narrow, whilst the compara- 
tively large optic thalamus carries the back part of the body of the ventricle outwards. 
This part of the ventricle in the idiot woman’s brain measures 8-5 thirtieths of an inch ; 
the anterior cornu 4, the posterior cornu 8, and the descending cornu 9 thirtieths. In 
the idiot boy the same parts measure respectively 6, 2*5, 7*5, and 8 thirtieths of an inch ; 
the body of the ventricle is therefore in both cases shorter than in the perfect brain, 
being shorter in the idiot woman than in the idiot boy, the length of whose parietal 
region has already been noticed ; the anterior cornu is also proportionally short, parti- 
cularly so in the idiot boy ; the posterior cornu is likewise short but wide, directed 
almost immediately backwards in the idiot boy, but divergent outwards in a remarkable 
manner in the idiot woman. The thickness of cerebral substance, between the end of 
the posterior cornu and the hinder edge of the cerebrum, is disproportionally great, 
being *4 inch in the idiot woman and *7 in the idiot boy. In the idiot woman the 
divergent direction of the point of the cornu makes it impossible to compare its rela- 
tive proximity to the apex of the posterior lobe with that observed in ordinary brains ; 
in the idiot boy the distance from the point of the cornu to the end of the posterior 
lobe, viz. *7 inch, is more than one-fifth of the total length of the brain, whereas the 
ordinary proportion is about one-eighth. The descending cornu, in correspondence 
with the size of the temporal lobe, is well and equally developed in both the idiots’ brains. 
The hippocampus major is large and wide in form, and terminates in front in an 
expanded and slightly sulcated extremity. The hippocampus minor is very wide, though 
short, in both brains ; in the idiot boy it is directed backwards, in accordance with the 
direction of the posterior horn ; whilst in the idiot woman it branches off outwards, in 
harmony with the divergent course of that cavity. The length of the hippocampus 
minor in the idiot woman is ‘8 inch, its greatest breadth - 35 ; in the idiot boy the length 
is *5 inch, and the greatest breadth ‘3. The eminentia collateral^ is distinctly visible 
in both brains. 
Measuring off the antero-median from the posterior portion of the cerebrum on 
Mr. Flower’s method, the ratio between the former and the latter is, in the idiot 
woman, 100 to 62‘2, in the idiot boy 100 to 61*9; so that the occipital region, as thus 
estimated, i. e. in its inferior layers, is proportionally longer in the idiots’ brains than in 
the perfect brain, or even than in the Chimpanzee’s brain, in which the proportions are 
