542 PEOFESSOE MARSHALL ON THE BEAIN OF A BUSHWOMAN; AND 
On the whole, the temporal convolutions, in both brains, are the boldest and best 
marked ; then the convolutions of the parietal lobes, especially in the idiot boy ; next 
stand the connecting convolutions and frontal rows, and those of the inner surface ; 
afterwards the orbital and occipital convolutions ; and lastly the island of Beil. 
4. On contrasting the idiots’ brains with one another, the convolutions generally are 
seen to be decidedly more developed in the idiot woman than in the idiot boy — the 
marked exception being in the parietal region of the latter, where the lobule of the 
posterior ascending parietal convolution, the supramarginal convolution on the left side, 
the bent convolution, and the adjacent second external connecting convolution are more 
fully developed. 
5. Agreeably to the opinions already expressed by other anatomists in regard to 
similar examples, the condition of the cerebra in these two idiots is neither the result 
of atrophy, nor of a mere arrest of growth , but consists essentially in an imperfect 
evolution of the cerebral hemispheres or their parts, dependent on an arrest of develop- 
ment (agenesie, asthenie-genie ) occurring at some stage or other of their metamorphosis 
from a simpler to a higher form. 
6. On comparing the condition of the cerebral convolutions of these brains with the 
representations of the brains of two foetuses at about 6^ and 7 months, published by 
Leuret and Gratiolet*, it would appear that in both idiots the convolutions are 
more complex than in the former, but less so than in the latter foetus. From this, one 
might hastily suppose that in both idiots the development of the convolutions, and 
indeed of the entire cerebra, had been arrested in the latter part of the seventh month 
of intra-uterine life; those of the idiot boy a little earlier than those of the idiot 
woman. 
But on further reflection such a supposition does not appear to be tenable, and it is 
not supported by facts. It necessarily assumes that, up to a certain period of develop- 
ment, the evolution of all the parts of the cerebrum had been normal in rate and in 
character ; whereas, in the first place, there is nothing at present to show why that rate 
may not, in such cases as these, be more or less retarded, so that any given stage is 
attained at a much later period than usual, and the ultimate condition of development 
be reached perhaps some time after birth ; and, in the second place, there is evidence in 
the brains themselves, of such a disproportionate development of parts as to prove that 
the normal character of the evolutional changes has been profoundly disturbed at some 
period or other, by at least one local departure from, or interference with the regular 
mode and order of development. 
A comparison of the size of the cerebellum and cerebrum in the idiots’ brains, and in 
the brain of a foetus at the seventh month, shows most strikingly that the development of 
the former organ had continued to progress long after the latter had experienced its final 
arrest ; but, what is more essential to the present inquiry, even within the idiots’ cerebra 
themselves there is proof that all the parts are not equally and normally developed. 
* Op. cit. pi. 30. figs. 1, 2, 3 ; pi. 31. figs. 1, 2. 
