588 NERVOUS SYSTEM 



in weight than the cerebellum. In man, also, not only the relative but 

 the absolute weight of the brain is greater than in the lower animals, 

 with but two exceptions. Todd has cited a number of observations 

 made on the brains of elephants, in which the weights ranged between 

 nine and ten pounds (about 4000 and 4500 grams). Rudolphi gave 

 the weight of the encephalon of a whale, seventy-five feet long (about 

 23 meters), as considerably over five pounds (about 2300 grams). With 

 the exception of these animals, man possesses the largest brain in the 

 zoological scale. 



Another interesting point in this connection is the development of 

 cerebral convolutions in certain animals, by which the relative quantity 

 of gray matter is increased. In fishes, reptiles and birds, the surface 

 of the hemispheres is smooth ; but in many mammals, especially in 

 those remarkable for intelligence, the cerebrum presents a greater or 

 less number of convolutions, as it does in the human subject. 



Development of the Cerebrum in Different Races of Men and in 

 Different Individuals. It may be stated as a general proposition, that 

 in the different races of men, the cerebrum is developed in proportion 

 to their intellectual power; and in different individuals of the same 

 race, the same general rule obtains. Still, this presents marked excep- 

 tions. Certain brains in an inferior race may be larger than the 

 average in the superior race ; and it is frequently observed that unusual 

 intellectual vigor is coexistent with a small brain, and the reverse. 

 These exceptions, however, do not take away from the force of the 

 original proposition. As regards races, the rule is found to be invari- 

 able, when a sufficient number of observations are analyzed ; and the 

 same holds true in comparing a large number of individuals of the same 

 race. Average men have an advantage over average women of about 

 six ounces (170 grams) of cerebral substance; and while many women 

 are far superior in intellect to many men, such instances are not suffi- 

 ciently frequent to invalidate the general proposition, that the greatest 

 intellectual capacity and mental vigor is coincident with the greatest 

 quantity of cerebral substance. If the view which is in every way 

 reasonable be accepted, that the gray substance alone of the cerebral 

 he^mispheres is directly connected with the mind, it would be necessary, 

 pigeoiomparing different individuals with the view of establishing a 

 stupor,"e relation between brain-substance and intelligence, to estimate 

 instinctivitity of gray matter ; but it is not easy to see how this can be 

 and the pch any degree of accuracy. 



of the spe-ndoubtedly true that proper training and exercise develop and 

 general sen^e vigor of the intellectual faculties, and that thereby the brain 

 ion that anin.in power, as are the muscles under analogous conditions. 



