424 



ORGAN SYSTEMS OF MAN 



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Fig. 16-22. Localized brain areas are concerned with special functions. 



number and extent of these increases as In general, the size of the brain is an indi- 



the brain increases in size, reaching a maxi- cation of intelhgence, although there are 



mum in man. Naturally, as the cortex has some notable exceptions, for instance, the 



increased in size, the entire brain has brain of both the whale and elephant weighs 



increased with respect to the cord. The rela- more than that of man. Dogs, gorillas, and 



tive weights of these two structures for sev- men of approximately the same body 



eral common animals are shown in the fol- weights have brain weights of about 140, 



lowing figures: 450, and 1350 grams, respectively. Within 



Ratio of limits of normal variation in a single species. 



Weight Weight brain size does not indicate intelligence. 



of Cord of Brain p^^ example, woman generally possesses a 



^^^ ^-^ ^'^ brain which averages about 100 grams less 



j^pj^j^gy I Q ]^5Q than man, but what man would be so brave 



Man 1.0 55.0 as to imply that she is less intelligent! Like- 



