MARSHALL ON THE BRAIN OF A YOUNG CHIMPANZEE. 299 



assume a position nearly parallel to the under surface of the brain, 

 instead of descending obliquely from it ; hence, the cerebellum falls 

 backwards further than in its natural state, presses somewhat aside 

 the posterior ends of the cerebral hemispheres, and so modifies the 

 proper relative position of these parts of the encephalon. Besides 

 this, the general subsidence of the cerebral hemispheres, the falling 

 asunder of the points of the middle lobes, and the sinking in of the 

 cerebellum between the hinder portions of the cerebrum, diminish 

 the concavity of the orbital surfaces, injure the concave outline of the 

 lower border of the posterior half of the hemisphere, and convert its 

 natural overhanging curve into a nearly even, oblique border, passing 

 backwards and upwards, above the cerebellum. All these changes, 

 which must be still more marked in brains already partially decom- 

 posed, will be better appreciated by comparing the photographic 

 illustrations of our Chimpanzee's brain given in Plate YI. figs. 2 and 4, 

 with the outlines, figs. 1 and 3, (also taken from photographs) of a 

 plaster cast, which I made of the interior of the cranium of the 

 animal, before the dura mater was removed from the bone, and iu which, 

 the divided tentorium was first carefully stitched up, on both sides. 



A comparison of these figures is of great interest, for it will not 

 only serve to elucidate a subject of controversy, just now of importance, 

 but it will demonstrate conclusively, that no proper estimate of the 

 general form of the encephalon, either of man or of brutes ; no exact 

 measurements of its parts ; and no correct idea of their mutual posi- 

 tions, can be obtained, unless by hardening the brain before it is 

 removed, or by correcting the notions derived from an examination 

 of this otherwise flaccid organ, by constant reference to the internal 

 form of the cranial cavity in which it was contained. M. Gratiolet 

 has been well aware of this fact and has availed himself of it in his 

 valuable researches ; but he has left an abundant field for future 

 observation. The internal forms of the crania of the different races 

 of mankind, especially, need to be systematically investigated and 

 measured in a similar manner. 



The illustrations which accompany this Paper will enable the 

 reader to follow me, in the critical examination which I here feel 

 called on to make, of the various original representations of the 

 Chimpanzee's brain given by Tyson,* Tiedemann,* Macartney,* 

 Schroeder van der Kolk and Vrolik,* and Gratiolet.* Tested by a 

 comparison with the brain and cranial cast in my possession, or 

 (as the reader must do) with the faithful facsimiles of those objects 

 taken by aid of photography, the figures given by these authors will 

 all be found to exhibit, unmistakeably, the Chimpanzee characters ; 

 but they differ materially in value. 



Tyson's figures are useless for modern science — in the main, owing 

 to their want of artistic rendering ; the basal view, as shown by the 

 position of the curved supra-orbital borders, is taken too much 



* In the works already cited by Professor Huxley and Dr. Rolleston in this 

 Keview. I am not aware of any other original figures of this brain. 



