578 THE POPULAR SCIENCE MONTHLY. 



the female than the negro the negress. The difference in the average 

 capacity of the skulls of male and female among modern Parisians is 

 almost double that between the skulls of the male and female inhab- 

 itants of ancient Egypt. . . . The general superiority, in absolute 

 weight, of the male over the female brain exists at every period of 

 development. In. new-born infants, the brain was found by Tiede- 

 mann to weigh from 14^ ounces to 15 ounces in the male, and from 

 10 ounces to 13^ ounces in the female. The maximum weight of the 

 adult male brain, in a series of 278 cases, was 65 ounces ; the mini- 

 mum weight, 34 ounces. The maximum weight of the adult female 

 brain, in a series of 191 cases, was 56 ounces ; the minimum, 31 ounces. 

 In a large proportion the male brain ranges between 46 and 53 ounces, 

 and the female between 41 and 47 ounces. A mean average weight 

 of 49 ounces may be deduced for the male, and of 44 ounces for 

 the female brain." It is further given, on the authority of Gratiolet 

 and others, that the male brain can not fall below 37 ounces without 

 involving idiocy ; while the female may fall to 32 ounces without 

 such a result. AH accepted authorities agree that the average male 

 brain exceeds the average female brain in weight by about ten per 

 cent. Professor Thurnam also adds, " The brain-weight of the male 

 negro is the same as that of the female European." 



Of qualitative differences of brain we know next to nothing ; we 

 can not study quality from the physiological side, but are driven to 

 an appeal to the concrete products of brain activity. Yet it is most 

 probable that we may at some time establish an exact correspondence 

 between brain-substance and intelligence, as the size and condition of 

 the lungs yield an exact measure of the breathing power, and as the 

 contractile muscle of the heart measures the quantity of blood ejected 

 at each pulsation. In the case of every other organ of the body we 

 know that there is an ascertainable correspondence between size and 

 condition, and the amount of work which the organ can do. Is there 

 any good reason for making an exception of the brain ? The plethys- 

 mograph (described in "The Popular Science Monthly" for July, 

 1880) measures the amount of blood sent to the brain in any particu- 

 lar process of thought, and records the exact time for each process. 

 We shall, doubtless, some time find it to be as complete a physical im- 

 possibility for a small and simply organized brain to do a great amount 

 of thinking within a given time as for a small heart to eject a large 

 quantity of blood at each beat, or for small lungs to absorb large 

 amounts of oxygen at each inspiration. Now, if we are not yet cer- 

 tain of the kind and degree of structural differences in the brains of 

 men and women, we still have overwhelming external evidence of the 

 existence of such differences. We have as much external evidence 

 of the superior quality of the masculine brain as of the superior 

 breathing power of the masculine lungs, or of the superior absorbing 

 power of the masculine stomach. We do not examine a muscle to 



