30 TABOO AND GENETICS 



the time of fertilization, depending 

 upon which type of sperm unites 

 with the uniform type of egg (in some 

 species the sperm is uniform while 

 the egg varies) ; 

 3. That this predisposition is : 



a. Weaker at first, before it builds up 



much of a body and gland system 

 to fix it ; 



b. Increasingly stronger as the new body 



becomes organized and developed ; 



c. Liable to partial or complete upset in 



the very early stages ; 



d. Probably quantitative — stronger in 



some cases than in others. 

 The new definition is, then, really a combination 

 and amplification of the three older points of 

 view. 



The term " sex determination " does not mean 

 to the biologist the changing or determining 

 of the sex at will on the part of the experi- 

 menter. This might be done by what is known 

 as " selective fertilization " artificially with only 

 the kind of sperm (X or Y as to chromosomes) 

 which would produce the desired result. There 

 is as yet no way to thus select the sperm of 

 higher animals. It has been authoritatively 

 claimed that feeding with certain chemicals, and 

 other methods to be discussed later, has affected 

 the sex of offspring. These experiments (and 



