THE DETERMINATION OF SEX 85 



products, which are characterized by the reduced number of 

 chromosomes. We are now in a position to distinguish sexual 

 elements and body cells by a visible microscopic character- 

 istic, and hence to define the two fundamental forms of cells. 

 A cell is only, then, a sexual element when it has the reduced 

 number of chromosomes. The sexual cells have sexuality. 

 The body in which the sexual elements are brought to develop- 

 ment may have sex. The basis of all clear thinking in 

 regard to the questions of sex is the difference between sex and 

 sexuality. 



How is sex determined? As yet we cannot explain the 

 relations in hermaphrodites at all. We know only that they 

 have indifferent sexual cells, out of which may be formed male 

 and female elements either at one time, or from time to time, or 

 at different periods of life. We assume that the occurrences 

 are regulated by internal conditions of the hermaphroditic 

 organism. We have also discovereji that external conditions 

 may under certain conditions influence the sexual develop- 

 ment of hermaphrodites, thus, for example, in melons, which 

 normally produce male and female flowers on the same plant, 

 under the influence of higher temperature only male flowers 

 develop, and under the influence of shade only female. How 

 these results come about is completely unknown. 



The investigation of forms of separated sex has proved 

 more valuable. Investigators have long endeavored to dis- 

 cover influences which might determine the sex of an ovum 

 during its development. For some time it was hoped to learn 

 something from the investigation of the proportion of the 

 sexes in various species. The sexual relation is usually cal- 

 culated by setting the number of females as = lOO, and then 

 expressing the number of males in percentage of the number 

 of females. These investigations have as yet yielded no 



