430 Mr Gregory, Some observations upon 



Some observations upon the Determination of Sex in Plants. 

 By R. P. Gregory, B.A., St John's College. (Communicated by 

 Mr W. Bateson.) 



[Read 29 February 1904.] 



The work which forms the subject of this paper has been 

 carried out to investigate the suggestion of Castle ('00), that sex 

 may be an inherited character exhibiting the Mendelian pheno- 

 mena of segregation and dominance. 



The way was prepared for Castle's suggestion by the work of 

 Cuenot ('99), and Strasburger ('00, b), who brought together 

 evidence which showed conclusively that sex cannot be determined 

 through the environment during the early life of the embryo. 



Strasburger, recognizing that the soma contains both sexes, 

 one in an "active," the other in a "latent" state 1 , discussed the 

 possibility of the segregation of the sex characters in the forma- 

 tion of the gametes; but rejected the hypothesis, mainly on 

 cytological grounds, but also on account of the difficulty of so 

 modifying it as to meet the case of those races in which one 

 sex is normally in numerical preponderance over the other 2 . 



Bateson ('94) and Bateson and Saunders ('02) draw a com- 

 parison between the phenomena of sex and those of variation. 

 This comparison is carried further by Castle ('03), who suggests 

 that " Sex is an attribute of every gamete, whether egg or sper- 

 matozoon, and is not subject to control through environment. It 

 is inherited in accordance either with Mendel's law of heredity, or 

 with the principle of mosaic inheritance." 



(1) The gametophyte in Plants. 



Accepting for the present the evidence which tends to show 

 that the chromosomes, or groups of chromosomes, contained in the 

 germ cells are the factors concerned in the transmission of 

 inherited characters 3 , and further the hypothesis suggested by 

 Cannon ('02), and independently by Sutton ('03), that the segre- 

 gation of characters in accordance with the Mendelian hypothesis 



1 See Darwin, Animals and Plants under Domestication, London ; John Murray. 

 2nd Edit., Vol. n. pp. 25—31. 



2 Certain factors affecting the numerical proportions of the sexes in man are 

 discussed by Punnett ("On nutrition and sex-determination in man," Proc. Camb. 

 Phil. Soc. Vol. xn. Pt iv.). 



3 See Wilson ('02) for an account of work previous to that date, and the more 

 recent work of McClung ('00, '02 a, '02 b), Boveri ('02, '04), and Sutton ('02). 



