14 TIIOS. H. MONTGOMERY, JR. 



follt>\\- such inheritance, the i In night originated of identifying 

 unit characters with chromosomes. It was made to appear that 

 unit characters are present in the germ, though just what relation 

 a rose coml> lias to a particular chromosome was not elucidated. 

 Mich a concatenation of ideas as this naturally led to the iden- 

 tification of "sex-units" with certain chromosomes. 



The better founded idea that the organism behaves as a 

 whole, whether it be a germ cell or a multicellular body, should 

 make iis lu-.il ate to localize any particular function solely in one 

 particular structure, for that would mean to disregard the im- 

 portance of interrelations of parts. Thus when we find partic- 

 ular chromosomes in one sex and not in the other, it by no 

 means follows that these are the cause of the sex difference. All 

 we can say at the present time is that the two phenomena are 

 coincident. Thus I am inclined to agree with Morgan's (1909) 

 closing thoughts: "The accessory (chromosome) may follow sex 

 or be associated with other differences that determine sex, 

 rather than be its sole cause." 



In all probability the activities of the chromosomes are in- 

 thiential in establishing sex, but not in the crude way in which the 

 process has been imagined. 



One point is quite clear, that fertilization is not necessary 

 for the establishment of sex, for any unfertilized egg that de- 

 velops furnishes a sexual individual. At the same time sex may 

 be changed by fertilization ; thus Whitney (1909) has shown it to 

 be probable that the male eggs of Rotatoria furnish males it noi 

 fertilized, but females when fecundated. Sex is then established 

 before, but may bechanced by fertilization. This clearly im- 

 plies that malcness and feinaleness are not unchangeable unit 

 chancier-, as does al-o the fact that an individual of one sex 

 may develop some of the characteristics of the other sex, a phe- 

 nomenon ><> apparent in the human body. Malcness and fern. ile- 

 tiess would appear to be two modes of one process, the proce-- 

 of germ cell production, not radically dill'erent conditions. In 

 oilier words, there i> no valid reason to interpret sex as an im- 

 mutable unit chancier resident in or presided over by particular 

 Chromosomes, and sorted oul and disiribuled by Mendelian 

 lion \\ilh all ihe complex mechanisms ol dominance and 



