ON THE BEAINS OF TWO IDIOTS OF EIJEOPEAN DESCENT. 
545 
and the parietal in the idiot boy ; the frontal lobe is also relatively a little larger in the 
woman. There can be no doubt also that the emotions, intelligence, and voluntary power 
of the woman were in advance of those of the boy ; but at present it would be premature 
to attribute too much importance to these probably individual anatomical differences, or 
to endeavour to associate them with peculiarities of psychological endowment. 
10. On contrasting the cerebral convolutions of the two idiots’ brains with those of a 
female and male idiot, each four years of age, represented by Leuret*, there appears a 
very close and remarkable resemblance between them. There is the same paucity, sim- 
plicity, and breadth of the convolutions, the same deficiency in the frontal lobes, though 
in one of them (the second referred to in the foot-note) to a less degree. The details of 
the convolutions are also nearly similar ; but in some slight particulars they are superior 
to those of the idiot woman, and especially so to those of the boy. For example, in both, 
the anterior ascending parietal convolution has passed beyond the stage of an intrusive 
convolution to that of an oblique smooth ridge of cerebral substance. There are also 
more numerous secondary sulci in most regions of the cerebrum, and the convolutions 
themselves are somewhat more tortuous. 
11. Lastly, on comparing the convolutions of the idiots’ cerebra with those of the 
Orang and Chimpanzee, they appear, in the human idiots, to be fewer in number than 
in the Apes, because, although the primary foldings correspond in each, they are indi- 
vidually less complex, broader, and smoother in the former than in the latter. In 
this respect the idiots’ brains are even more simple than the brain of the Gibbon, and 
approach that of the Baboon (Cynocephalus) and Sapajou (Ateles)f. 
As special and interesting results of this general simplicity of the primary convolu- 
tions, are the absence, as in the quadrumanous brains, of such a development of the 
supramarginal convolution as to constitute its so-called lobule, and the partial conceal- 
ment of the upper external connecting convolution, as well as the imperfect develop- 
ment of the anterior ascending parietal convolution, and the extreme simplicity of the 
bent convolution. Of these, the non-development of a distinct supramarginal lobule is 
the most interesting defect, since it indicates the late appearance in the brain of a part 
whose presence is regarded by Gratiolet as peculiarly characteristic of Man. 
On the other hand, the points of special difference between the idiots’ and the qua- 
drumanous brains, both general and particular, are even more numerous. First, as a 
general difference, there is a remarkable want of symmetry even in these imperfectly 
developed cerebra, as if already preparations were being made to establish that higher 
and almost exclusively human character ; this point has been so frequently exemplified 
in the previous descriptions that we may refer to them for abundant illustration of it. 
Secondly, the special differences, which likewise exhibit the decidedly human character, 
are the superficial position of all four of the external connecting convolutions ; the con- 
sequent speedy interruption of the external perpendicular fissure, and complete oblitera- 
tion of its posterior border or operculum ; the concealed position of the lower internal 
* Op. cit. pi. 24. fig. 4; pi. 32. figs. 1 to 5. 
t Gbaiiolet, pi. 4. figs. 1 & 2; pi. 9. figs. 1 & 4; pi. 10. figs. 1 & 2. 
