i6 



GENETICS 



Figure 4. This and figure 5 are diagrams to illustrate the chromo- 

 some combinations in the formation of germ cells, in males and fe- 

 males. The chromosomes of Protenor (figure 3) are employed as the 

 basis of the diagram. The chromosomes of the male are represented 

 in outline, at A; the chromosomes of the female in solid black, at B. 

 At the left is represented in each case a cell of the parent individual, 

 in the male with six pairs of autosomes and one X ; in the female 

 with six pairs of autosomes and two X's. At the right are the germ 

 cells. Half of the germ cells from the male have an X, half do not; 

 while all the germ cells from the female have an X (see figure 5 

 for continuation of the diagram). 



characteristic differences between the male and the female 

 go back to this difference of one chromosome in the cells 

 that produce them. 



For we find that the eggs that contain the full set of 



