Tllns. II. MONTGOMERY, JR. 



dt" tin- connection between heterochromosomes and sr\-deier- 

 niin.ttiiin i- accordingly imt disturbed by this discovery." 



Morgan [909, I'm"! classes the theories of sex determination 



by chroiuo-oi qualitative ,ind (|ii.uit itat i\ e, and incline- to 



the latter \ iew he bring the first to take this stand positively. 

 By a quantitative interpretation In- does "not mean that the 

 triii. dc is simply male plus something rl-e, a view recently ad- 

 \anced hy Castle, but that male and female are two alternate 

 of ilu' li\'ing material, which poihilit\- is realized 

 on quantitative factors. . . . The gametes are not, 

 therefore, male and female, but contain certain factors which, 

 when combined, -i\< rise, in an epigenetic fashion, to one or the 

 other altcrnath e." In the phylloxerans, the "loss of certain 

 chromosomes from the male egg appear- to follow, not to pre- 

 cede the -i/e relation. . . . But there i- nothing in these facts 

 that -how-- that- the effect^ are directly quantitative rather than 

 that observable quantitative differences accompany, or follow 

 in some cases, more profound changes." He considers as the 

 most -eiious objection to the qualitative interpretation "that 

 although the hypoihe-i- is ostensibly based on the presence of 

 certain chromosomes which are assumed to be male and temale 

 running respectively, yet to these chromosomes, which are 

 to all appearances identical, are ascribed exartly opposite func- 

 tion-." Morgan's whole attitude i> rather hostile to the view 

 that particular chromosomes are sex-determinant-, and his argu- 

 insl the \ iew are the- most cogent yet presented. 



C. FURTHER CRITICISMS OF THE Hvmi in >is. 



In a pivxioii- treatment (ic^oGa) of the phenomenon of sex- 

 uality, I \va- led to define it (p. *5 ) as "essentially t hi- condition 

 of ditteicnce obtaining between conjugating individuals...- 

 Because conjugation is a pn>< . distinct from reproduction, sex- 



Uality, being intimateK associated wit h conjugal i>n, has no jiri- 



mary connection with reprodut tion. . . . The genesis of sexuality 

 has been this: that out of a state where all individuals were equally 

 capable of reprodm lion aconditionof division of labor has ensued, 

 inducing morpholo-ji al and chemical differences, between individ- 

 uals capable of re|>rodui tion and conjugation and other individuals 



