ON THE BRAINS OF TWO IDIOTS OF EUROPEAN DESCENT. 
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mass, the temporoparietal region predominates in both brains, whilst the occipital and, 
especially, the frontal are defective. 
Contrasting the idiots’ brains with the Orang-outang’s or the Chimpanzee’s brain, the 
frontal lobe is still small, especially in the idiot boy ; the parietal lobe occupies, on the 
whole, proportionally a larger space, whilst the occipital lobe occupies less. The tem- 
poral lobes are relatively much larger and fuller, but shorter than in the Chimpanzee’s 
brain. The central lobe is much less developed ; for in the Chimpanzee this part, com- 
pletely concealed as in Man, has five radiating convolutions ; whilst in the idiot woman’s 
brain it consists only of a slight smooth eminence ; and in the idiot boy no very distinct 
elevation of the surface can be detected. 
The Convolutions. — The orbital convolutions (Plates XXI. & XXII. figs. 11 & 15, u—um) 
are remarkably simple, being only slightly marked off from one another, and very 
smooth. In the i’diot woman’s brain (Plate XXI. fig. 11), the sulci which lodged the 
olfactory nerves are very short and shallow, especially that (o) on the left hemisphere ; they 
are represented in the idiot boy’s brain (Plate XXII. fig. 15) by a slight linear depres- 
sion only on the right hemisphere, and a still smaller depression on the left. The deep 
triradiate sulci which cut up the orbital surfaces in the perfect cerebrum in so complex 
a manner, are much simplified in both the idiots’ brains ; they are more developed in the 
woman’s than in the boy’s brain, and in both cases are more developed on the right 
than on the left hemisphere. On the right hemisphere of the female idiot brain alone 
is this sulcus distinctly triradiate ; on the left hemisphere it is more irregular. In the 
idiot boy it is represented on the right by a shallow longitudinal sulcus, on the left by 
a slightly curved one. Accordingly the orbital surfaces are much less complex and 
smoother even than in the Ape ; at the same time, with all their simplicity, the want 
of symmetry of the two sides is remarkable. 
The three rows of frontal Convolutions (Plates XXI. & XXII. figs. 10, 12, 14 & 16) 
can be distinguished on each side, above the orbital border, in both the idiots’ brains. In 
the idiot woman (figs. 10 & 12), the inferior row ( i ) is represented by a short, simple, 
horizontal convolution, which speedily joins the anterior ascending convolution behind 
and the middle frontal row in front. This middle row (2) consists likewise of a single 
convolution bent once outwards. The upper row ( 3 ), as usual, larger and more complex 
than the others, occupies half the frontal lobe, but is still remarkably simple in form. 
The upper frontal row, as ordinarily, blends with the upper end of the anterior ascend- 
ing parietal convolution; the middle row is joined to that convolution near its lower 
end, by the same connecting ridge as the third row. In the idiot boy (figs. 14 & 16) 
the three rows can be distinguished, but are still more simple in their form and direc- 
tion. The three rows are more equally developed, the inferior row being relatively well 
pronounced, giving a proportional breadth and squareness to that part only of the frontal 
lobe, not noticeable in the female brain. Easily discriminated in the idiots’ brains, 
both as to their position and connexions, chiefly owing to their great simplicity, these 
frontal convolutions are singularly short and defective as compared with their wonder-- 
4 b 2 
