Sex Determination 183 



same fundamental facts in different terms or by the use of 

 different -indices; (3) the claim that both are true but 

 cover different territories; that one of them explains 

 certain types of cases and the other explains other types 

 of cases. At present the third alternative seems to be 

 the most reasonable and least difficult of explanation. 



In view of the evidence on both sides one can hardly 

 say that either the chromosome theory or the physio- 

 logical theory is absolutely wrong. Again, to interpret 

 either theory in terms of the other is theoretically very 

 difficult. The cytologists certainly present a striking 

 demonstration of the chromosome theory, showing 

 the sex chromosomes and the constant occurrence of the 

 proper numbers in a given sex. They also show the 

 machine at work with its inevitable sex product of 50-50; 

 and of course they are logical in concluding that sex 

 cannot be controlled. 



On the other hand, the physiologists show just as 

 clearly that sex can be controlled artificially; by chan- 

 ging the chemistry or physics of the situation they change 

 the sex. This of course is cytologically unorthodox; 

 and as a consequence some cytologists have attempted 

 to clear up the situation by the following claim. Granted 

 that certain chemical changes may change the sex, 

 the result is due to the fact that the mitotic figures are 

 disturbed and the sex chromosome situation changed. 

 It is always the sex chromosomes that determine sex, 

 but they may rearrange themselves in consequence of 

 abnormal chemical stimuli. Such an explanation seems 

 like the last resort. One might imagine that the nucleus 

 might cast out a sex chromosome and thus change an 

 expected female into a male ; but to make the change in 



