298 Proceedings of the Royal Physical Society. 



months, and having its membranes taken off, its weight was 

 reduced to 8J ounces. 



The weight of this brain is a little less than one described 

 by Professor John Marshall/ as in the latter it weighed 

 15 ounces immediately after its removal from the cranial 

 cavity and 9 ounces after hardening in spirit for several 

 months. Professor Marshall's specimen was a male 1 J inches 

 taller than mine, but its dentition was not quite so advanced, 

 as the upper first permanent molars had not erupted. My 

 brain probably lost an ounce or so while in the cranial 

 cavity by being injected with spirit, which would remove 

 some of its water and dissolve some of its. salts. Miiller^ 

 gives a list of the weights of the brain in nine cases, — viz. : 

 two by Owen, and one each by Marshall, Bischoff, Chapman, 

 Parker, Drell, and himself. Of these specimens Marshall's 

 is the heaviest and Miiller's the lightest, the latter weighing 

 only 9 J ounces. 



In Dr Chapman's ^ case the brain weighed only 10 ounces 

 and 10 grains, although his chimpanzee was fully as tall as 

 Marshall's. In addition to the cases mentioned by Miiller, 

 other specimens have been described by Embleton and 

 Bischoff, but they do not affect the general resu'lt, which 

 may be stated as follows : — the average weight of the brain 

 of a chimpanzee, with its milk teeth in position and its first 

 permanent molars erupted, or about to do so, and its height 

 betw^een 2 feet and 2 J feet, is probably not more than 12 or 

 13 ounces. We have unfortunately no account of the brain 

 of the adult chimpanzee, all those hitherto described belong- 

 ing to young individuals, which may be considered to 

 correspond to children between two and four years of age. 

 The brain of the latter is about three times heavier than 

 that of the chimpanzee. Thus Boyd^ found the average 



1 On the Brain of a Young Chimpanzee — Natural History Review, vol. i,, 

 1861. 



2 Zur Anatomie des Chimpansgehirn — Arch, fiir Anthropologie, Bd. xvii., 

 1888. 



3 On the Structure of the Chimpanzee— Proceedings of the Acad, of Natural 

 Science of Philadelphia, 1879. 



^ Philosophical Transactions, 1860. 



