364 ELEMENTARY ZOOLOGY. 



group of his own. These great improvements in powers 

 have accompanied and are in some measure due to the 

 gaining of the upright position and to the use of the 

 hands as the instrument of the brain and to the develop- 

 ment of spoken language. These three things the en- 

 larging brain, the free hands, and the growing language 



FIG. 157. Brain of Gauss, the mathematician. From Mill's "Text-Book of Animal 

 Physiology; "Copyright D. Appleton & Co. Lettering as in Fig. 155. 



Questions on Figs. 155-157. Identify and compare the cerebrum 

 in these three brains. What are the chief differences? Compare 

 the mass in front of the fissure of Silvius (that is, the frontal lobe), in 

 the three. What is the reason of the connection between the 

 numerous convolutions and mental development? Which increases 

 more, the cerebrum or the cerebellum, as we ascend the scale? 

 The meaning of this? 



would tend to train and improve one another. The brain 

 working through the hands, means the making of imple- 

 ments, of dwellings, and of numerous forms of mastery 

 over nature. The brain working through language and in 

 the more intimate parental relations brought about by 

 homes, makes possible education and the training of the 



