146 FERNANDUS PAYNE. 



manner of the separation, it is in regard to the behavior of the 

 small chromosomes. Fig. 10, O, a side view of an early anaphase, 

 and Fig. 10, P and Q, pole views of the early anaphases, demon- 

 strate clearly the behavior of the large and two medium sized 

 ones. A number of anaphases showing one and two small chro- 

 mosomes were present (Fig. 10, and P), and when present, 

 they were always with the two medium sized ones and not with 

 the large one. A thorough study of many anaphases showing 

 the large chromosome, has in no case, revealed the presence of 

 a small one (Fig. 10, P). Further, the number of chromosomes 

 and their size relations in the male and female cells makes it 

 almost conclusive how the hexad group separates. As previously 

 stated, the female group has 30 chromosomes, six of which are 

 very small, and the male group has 26, three of which are small 

 and one very large. If five members of the hexad group go 

 to one pole and one to the other, two classes of spermatozoa are 

 produced, containing 15 and n chromosomes respectively. The 

 i5-chromosome class will contain 12 chromosomes of nearly 

 equal size and three very small ones. The n-chromosome class 

 will contain ten chromosomes of approximately equal size and 

 one very large one. Now, if the 15-chromosome class meets an 

 egg with 15 chromosomes, three of which are small, the cells 

 of the resulting individual will have 30 chromosomes, six of 

 which will be small. This condition is fulfilled in the female 

 chromosome group. If the same egg is met by the n-chromo- 

 some class of spermatozoa, the cells of the offspring will contain 

 26 chromosomes, three of which will be small and one very large. 

 This is the number and size relations found in the male cells. 

 No other manner of separation of the hexad group could bring 

 about a similar end result. It becomes evident then that the re- 

 duced number of chromosomes in the egg is 15, and that females 

 are produced upon fertilization by the i5-chromosome class of 

 spermatozoa; males upon fertilization by the n-chromosome 

 class. 



Egg 15 plus spermatozoon n= = 26 (<), 

 Egg 15 plus spermatozoon 15 ==30 ($). 



As previously stated, the material which I have, does not 



