38 TABOO AND GENETICS 



of the fittest and elimination of the unfit) is the 

 mechanism of evolution or progress which best 

 accounts for the observed facts. Such varia- 

 tion is called " chance variation," not because 

 it takes place by " chance " in the properly- 

 accepted sense of the term, but because it is so 

 tremendously varied — is evidently due to such 

 complicated and little-understood circumstances 

 — that it can best be studied mathematically, 

 using statistical apphcations of the " theory of 

 probabilities." 



The fine-spun, elaborate theories about sex, 

 so current twenty years ago, have fallen into 

 almost complete desuetude among scientists. 

 With the discovery of the place of the chromo- 

 somes in inheritance, biologists began to give 

 their almost undivided attention to a rigid 

 laboratory examination of the cell. This has 

 included sex phenomena since McClung and 

 Sutton pointed out the function of the sex 

 chromosome in 1902 and 1903. Present-day 

 " theories " are little more than working hy- 

 potheses, developed, not in a library or study, 

 but with one eye glued to a high-power micro- 

 scope. 



Besides its faulty foundation as to facts, the 

 old gynaecocentric theory involved a method of 

 treatment by historical analogy which biologists 

 have almost entirely discarded. Anyone in- 

 e rested in the relative value of different kinds 



