LECTURE IV. 107 



The convoluted brain of man resembles tlie smootb brain of 

 the Ouistitis in the characteristics of a rudimentary olfactory 

 bulb ; a posterior lobe, which entirely covers the cerebellum ; 

 a perfectly marked Sylvian fissure, and a posterior cornu in the 

 lateral ventricle of the brain." [Gratiolet might have added a 

 fifth character, the existence of a central or intermediate lobe, 

 which occurs in all apes.] 



" These characters," continues G-ratiolet, " coexist only in 

 man and the ape. The cerebellum is uncovered in all other 

 animals ; we mostly find an enormous olfactory bulb, as in the 

 elephant ; and vsdth exception of the makis {Lemuridce) no 

 animal presents a fissure, hke the Sylvian, with an enclosed 

 central lobe. 



" Thus, there is a cerebral form peculiar to man and ape ; 

 and so in the cerebral convolutions, wherever they appear, 

 there is a general unity of arrangement, — a plan, the type of 

 which is common to all these creatures. 



" This uniformity in the arrangement of the convolutions in 

 man and ape deserves, in the highest degree, the attention of 

 naturalists. Thus, in the makis {Lemuridce), cats, dogs, bears, 

 in short, in all families a peculiar type of convolution is found. 

 Each of these families has its own character; and we can 

 arrange the different species within any group by examining 

 the convolutions." 



So far Gratiolet. It seems to me to follow necessarily from 

 these words, that it is requisite to study the convolutions more 

 closely, since, as we shall see, their development is, no doubt, 

 connected with that of the human type and also with intelligence. 

 In order to proceed upon a definite basis, it is best to com- 

 mence with a side view, and to start from the Sylvian fissure, 

 which is most distinctly marked in all human and ape-brains 

 (see fig. 31). As already observed, the Sylvian fissure divides 

 into two branches : an anterior, nearly perpendicular ; and a pos- 

 terior, nearly horizontal, which, however, usually turns upwards, 

 so that the Sylvian fissure, on the whole, takes the form of a 

 V. Between these two branches there is thus marked off a por- 

 tion which might be called the lateral middle lobe, which some 

 authors include in the frontal, and others in the parietal lobe. 



