Inheritance Materials of Germ-Cells 79 



eggs produced in the spring will produce all or nearly all 

 males. The last several pairs of eggs laid in autumn will 

 produce all, or nearly all, females. At the transition period 

 in the summer he found that some pairs, or clutches, of eggs 

 produced both a male and a female. In these cases it was 

 usually the first egg that produced the male ; and the sec- 

 ond egg laid forty hours after the first that gave rise 

 to a female." 4 



Into Riddle's interesting discussion of Whitman's results 

 and his own chemical studies on the eggs of pigeons and 

 hens we need not go. Suffice it to say that it seems to me 

 Riddle is justified by the evidence now in our possession, 

 in his contention that "sex rests upon a quantitative and 

 reversible basis" and that in this sense it has been controlled 

 by conditions extraneous to the germ-cells themselves. This 

 does not imply, as I understand, that such control would 

 necessarily be practicable or even possible in all organisms, 

 nor does it preclude the possibility that in some species 

 there may be dimorphic or partially dimorphic spermatozoa 

 or ova as regards sex production. Neither does it preclude 

 the possibility that in some cases where a preponderance 

 of one sex has been observed, this is due to selective mor- 

 tality or some process other than the actual shifting of the 

 sex tendency in the particular eggs. 



These several concordant bodies of testimony must, it 

 would appear, open the eyes of biologists sooner or later to 

 the ludicrousness of a theory that would make the parent 

 organism hardly more than a combined culture medium and 

 incubating oven for its germ-cells. 



The Determiner Conception Contrary to Ordinary Chem- 

 ical Principles 



If, on the basis of such facts as we have, we try to come 

 still closer to the questions of how the assimilative and 

 morphogenic processes of the organism occur, whether in 



