C. J. Bond 345 



of the relative position assumed by the factors for maleness and feinale- 

 ness in those qualitative cell divisions which control the segregation of 

 the sex organs. Thus if maleness passes into the lateral daughter cells, 

 while femaleness is retained in the cells which continue the axial line 

 of growth the flower although hermaphrodite is primarily female. If 

 on the other hand (as in these abnormal Begonia flowers) femaleness 

 is thrown off into the lateral daughter cells and maleness remains in 

 the central cells then the flower although still hermaphrodite is primarily 

 male. 



It is in fact even more true of plants than animals that sex is a 

 function of the position of the factor or factors which control it. 



These abnormal Begonia flowers, primarily male and primarily 

 female, also show that under certain conditions the qualitative cell 

 divisions which determine sex may be imperfect or incomplete. Thus 

 if the type of the division has been settled by the passage of the factor 

 for maleness into the central daughter cells, then any remnant of the 

 female factor if present must apparently pass into the lateral daughter 

 cells. This fact suggests some association between the volume of the 

 ftxctor and the position assumed by that factor in cell division. The 

 conception is indeed forced upon us that the sex of a unisexual flower 

 on a monoecious plant partly depends on the relative volume of the sex 

 factors present in that flower. Whether the male organs shall occupy 

 a central or a circumferential position on the floral axis (in other words 

 whether the flower shall be male or female) seems to depend partly on 

 whether the factor for maleness is present in greater volume than the 

 factor for femaleness. If it is, then maleness is handed on to the 

 daughter cells in the direct line of growth and the flower is primarily 

 male, whereas if the volume of the female factor is greater than that of 

 the male factor, then femaleness continues in the line of growth and 

 maleness is cast off into lateral daughter cells. 



The importance of this matter lies in the fact that sex segregation 

 in the flowers of monoecious plants seems to be associated with a definite 

 position assumed by the alternative fixctors which control sex either in 

 one or in a series of qualitative cell divisions. 



One may perhaps hazard the suggestion that if future cytological 

 research should associate the male (or the female sex) in the Begonias 

 with the presence of an accessory chromosome, then the position 

 taken up by that accessory chromosome in the qualitative cell divisions 

 which divide the growing cell into end on and lateral daughter cells 

 will determine the primary sex of the flower, just as the passage of such 



