116 THE RELATIONS OF MAK 



sothrix)^ the cerebral lobes overlap and extend mncli fur- 

 ther behind the cerebellum, in proportion, than they do 

 in man (Fig. lY) — and it is quite certain that, in all, the 

 cerebellum is completely covered behind, by well devel- 

 oped posterior lobes. The fact can be verified by every 

 one who possesses the skull of any old or new world mon- 

 key. For, inasmuch as the brain in all mammals com- 

 pletely fills the cranial cavity, it is obvious that a cast of the 

 interior of the skull will reproduce the general form of the 

 brain, at any rate with such minute and, for the present 

 j)urpose, utterly unimportant differences as may result 

 from the absence of the enveloping membranes of the 

 brain in the dry skull. But if such a cast be made in 

 plaster, and compared wdth a similar cast of the interior 

 of a human skull, it will be obvious that the cast of the 

 cerebral chamber, representing the cerebrum of the ape, 

 as completely covers over and overlaps the cast of the 

 cerebellar chamber, representing the cerebellum, as it 

 does in the man (Fig. 21). A careless observer, forgetting 

 that a soft structure like the brain loses its proper shape 

 the moment it is taken out of the skull, may indeed mis- 

 take the uncovered condition of the cerebelhim of an ex- 

 tracted and distorted brain for the natural relations of the 

 parts ; but his error must become patent even to himself 

 if he try to replace the brain within the cranial chamber. 

 To suppose that the cerebellum of an ape is naturally un- 

 covered behind is a miscomprehension comparable only to 

 that of one who should imagine that a man's lungs always 

 occupy but a small portion of the thoracic cavity — because 

 they do so when the chest is opened, and their elasticity 

 is no longer neutralized by the pressure of the air. 



And the error is the less excusable, as it must become 

 apparent to every one w^ho examines a section of the 

 skull of any ape above a Lemur, without taking the 



