4O2 



J. SEILER. 



(&) Maturation of the Sperm. In the spermatogenesis no 

 sex-chromosomes can be distinguished. The equatorial plates 

 of the first maturation-division show 30 chromosomes (Figs. 

 26, 27) and those of the second division the same (Fig. 28). 



TABLE II. 



(c) The Somatic Chromosome-number. Since two classes of 

 eggs are formed, having respectively 29 and 30 chromosomes, 

 we may expect to find two kinds of embryos, one having 59 

 chromosomes, the other 60. The actual conditions correspond 

 with this expectation. In the stage of blastoderm-formation it 

 is possible to count the somatic chromosome-number with abso- 

 lute certainty. Figs. 15 and 16 show 60 chromosomes, though 

 not so clearly as the actual object. Table III. gives a summary 

 of the observed cases. Only such embryos were recorded as 

 showed at least 2 (often 4 to 6) perfectly clear equatorial plates, 

 each of which lay entirely in a single section and in the middle of 

 its thickness, and in which no doubt could exist concerning the 

 limits of a single chromosome. 



TABLE III. 



Locality. Embryos. 

 Tornow 30 



25 



" 4 



No. of 



Chromosomes. 



59 

 60 



58 



As the table shows, a third sort of embryo could be demon- 

 strated possessing 58 chromosomes. This determination can 

 not possibly rest on an error, for in the first embryo seven per- 

 fectly clear plates all showed 58 chromosomes, in the second 6, 

 in the third 5, and in fourth 2. Such embryos would probably 

 produce but one kind of egg, containing 29 chromosomes. In 



