The state of emaciation in which this child is reported to have died makes it the fairer to take it as a standard in this comparison. The child's dentition may very well have been in the same state as that of our orang; its age, however, was in all likelihood much further advanced; but as the brain would have been growing rapidly during those years, whilst the weight of the body was not increased proportionally, the excess of years may not in reality have caused in this case any diminution in the relative disproportion of the child's brain to its body, as it does in cases of healthy development.
On the other hand, we must recollect that the proportion subsisting between the adult brain in man and the body has been put as low as 1 : 50;[1] and that though this proportion is lower by as much as 15 than most authorities would rate it, some such disproportion must have prevailed in those cases in which the brain of an adult Negro is recorded as reaching no greater weight than 753 grammes[2] or 1 lb. 10.59 oz.
The weight of the body of a nearly adult female chimpanzee is given by Professors Sharpey and Ellis, on the authority of Professor Owen, as 61 lb. The relation of weight between such a body and the brain of our orang which weighed 12 oz. would be 1 : 81.3.[3]
Let us suppose that the Negro, the weight of whose brain, as given by Tiedemann, amounted to no more than 26 oz., weighed altogether as much as 8 stone, or 1792 oz. The proportion between his brain's weight and his body's would then have stood as 1 : 68.9, as against a proportion taken between analogous weights in the apes of 1 : 81.3. It will be seen from this that the absolute weight of the human brain is a more sharply differentiating characteristic than is its relative weight.
It will be convenient to give the following measurements and their mutual relations in a tabular form, using, for the sake of economy of space, the letters of the alphabet to denote each particular measurement:—
a. The length from the root of the olfactory nerve to the anterior extremity of the brain.
b. The length from the point of the middle lobe to the posterior extremity of the brain.
c. The length of the cerebellum.
d. The breadth of the cerebellum.
e. Length of cerebral hemispheres.
f. Length of corpus callosum.
| a : b | In Orang = 134 inch. : 278 inch. = 1 : 1⋅64. | |
| In Man = 258 inch. : 518 inch. = 1 : 1⋅95. | ||
| In Chimpanzee[4] = 44 mm. : 69 mm. = 1 : 1⋅56. |
