72 THE POPULAR SCIENCE MONTHLY. 



son from product to structure until after we have internal evidence of 

 the functional relations between the structure and product of the class 

 of organs to which those under test belong ; nor can we without such 

 knowledge even reason to the general quality of two organs by their 

 different product, unless our comparisons are made under the same 

 . environment. For instance, take two pairs of lungs : let one respire at 

 sea-level, the other at the top of Mont Blanc. Their absolute product 

 would be no estimate of their relative capacity. Still, the physiologist 

 would have little difficulty in eliminating the effect of difference of 

 circumstances in his calculation, because his complete knowledge of 

 the lungs and of the influence of atmospheric pressure enables him to 

 allow for differences of environment. But no such allowance can be 

 made in estimating the normal power of the male and female brain 

 which have always acted in different mental atmospheres ; for the 

 relation of structure to function as regards brain has not been accu- 

 rately determined. 



It is because of this lack of knowledge regarding the precise con- 

 nection between brain-structure and thought, and not because of im- 

 perfection in the data of measurements, that students refuse to draw 

 therefrom the law of brain capacity ; and thinkers will not infer the 

 capacity of male and female brains from their products, until the 

 different influences acting upon men and women can be eliminated. 

 While anatomy is unable to solve for us the enigma of sexual brain- 

 power, we may have recourse to comparison under similar environ- 

 ment as the key to our problem. This method of discovery Miss 

 Hardaker, with a perversity remarkable in a disciple of modern science, 

 is laboring zealously to prevent. 



" We need not," she says, " ascertain the meaning of brain-size by 

 experiment ; we can arrive at it by analogy. All other organs (under 

 the same conditions) work in proportion to their size. Is there any 

 good reason for making an exception of the brain?" (page 578). 

 Now, even if all other organs work in proportion to their size, the fact 

 that the brain is exceptional, in the nature and in the variety and 

 complexity of its functions, would render the argument from biceps to 

 brain as questionable as that from marble to zinc. There may be prop- 

 erties in common, but in the production of forces the similar effects of 

 these common properties may be wholly vitiated by others peculiar to 

 only one of the objects compared. Besides, size is not always a gauge 

 of organic capacity. Does the large eye see better, the large ear hear 

 more, the large nerve feel more keenly ? And, if, all other conditions 

 being equal, they might do so, the incalculable variation of condition 

 renders the size test of no practical value at all. This, however, is a 

 phase of the subject to be discussed later, when we shall endeavor to 

 show that, although we agree with Miss Hardaker that a larger brain 

 means something, it does not necessarily mean a " greater amount of 

 thinking in a given time." And, here we throw in, as interesting 



