78 The Unity of the Organism 



the ^ggi and that it may depend in some way on the rela- 

 tive amount of water in the ^gg at the time of fertiliza- 

 tion." 3 



Riddle, perhaps the most outspoken opponent of sex pre- 

 destination now writing, strongly espouses the hypothesis 

 that the sex to which a particular Qgg will give rise is de- 

 pendent partly on the quantity of water which that Qgg 

 contains. But whether water is a factor in determining sex 

 or not, the evidence presented by Riddle, coming partly from 

 researches by C. O. Whitman and partly from his own, 

 constitutes, when taken with the evidence to the same effect 

 presented by other investigators, almost if not quite com- 

 plete proof that sex is not the hard-and-fast thing which 

 most present-day genetic speculation would make it. 



Furthermore the evidence produced by these two inves- 

 tigators seems to connect the decision as to which sex a 

 particular ^gg shall give rise, with some condition of the 

 parents. It is well known to all zoologists, in the United 

 States at least, that at the time of his death Professor Whit- 

 man had accumulated a vast store of data on the habits, 

 particularl}'^ the breeding habits, of pigeons. To Doctor 

 Riddle, who had worked with Whitman considerably, fell 

 the task of carrying on to some extent Whitman's experi- 

 ments and of preparing for publication the results which 

 Whitman left in the rough. The following quotation from 

 Riddle's paper referred to above, summarizes Whitman's 

 results that are especially important for us now: "Whit- 

 man found that if certain very distantly related pigeons 

 [i.e., two individuals from different families] are mated 

 that only male offspring resulted. If the matings were 

 made of individuals not quite so distantly related — different 

 genera usually — and if to this situation be added the ele- 

 ment of overwork at reproduction [i.e., the birds not being 

 permitted to nest their own eggs, but forced to keep laying 

 eggs in rapid succession] then the first several pairs of 



