102 THE DETERMINATION OF SEX 



A. Diploid cells. 



1. Cells of the female bcdy. 



2. Cells of the male body. 



B. Haploid cells. 



3. The female elements (mature ova and polar 

 globules) 



4. The male elements (spermatozoa). 



We suspect besides that there is a fifth kind of cell, the 

 indifferent, which we shall perhaps later learn to recognize 

 in hermaphrodites and lower organisms. 



Thus we reach the conclusion of to-day's lecture. We 

 advance the hypothesis that sex rests upon a physical basis, 

 which we recognize by differences in the proportion of chro- 

 matin in the cells of the male and female body. The epoch- 

 making discoveries of my American colleagues awake joyful 

 excitement among biologists. We are pupils of German 

 science, and in carrying out the investigations, the results of 

 which I have presented to you today, our investigators have 

 striven to equal the German ideal. May our activity express 

 to you our gratitude ! 



