ARTIFICIAL PARTHENOGENESIS 193 



a male, but if sex is a relation of X to ABC, one cannot 

 be certain that it might not be a female. 



In cases where the female is heterozygous for the 

 sex factor, as in birds and some sea urchins, the formula 

 for the female would be XABCD — YABCD and for 

 the male YABCD — YABCD. There would be two 

 types of eggs, XABCD and YABCD. The former 

 might be expected to produce a female, the latter prob- 

 ably a male if such eggs were incited artificially to 

 develop. 



Concerning the sex of the embryos so far produced 

 by artificial parthenogenesis, we know of only two 

 cases. These two cases are Delages' result for the 

 sea urchin, in which he got one male, and Loeb's and 

 Bancroft's case for the frog, in which they believe that 

 the two young obtained were females. 



What to expect on theoretical grounds is uncertain. 

 We have only two facts that bear on the question. 

 In the parthenogenetic eggs of the aphid, with the for- 

 mula XABC ABC we get a male. In the case of the 

 bee the formula is XABC, which also gives a male. All 

 else is hypothetical and premature, but if these two 

 formulae are correct, it appears that one X gives a 

 male and that maleness is not due to a quantitative 

 relation between X and one or two sets of the other 

 chromosomes. It is the quantity of something in X, 

 not the relation of this to the rest of the chromosomes. 



