144 KANSAS UNIVERSITY SCIENCE BULLETIN. 



taken to repeat these counts, and there is every reason to be- 

 lieve that they are approximately correct within a very short 

 margin of error. 



Table showing number of sex-cells in embryos varying in 

 size from a total length of 3 mm. to 7 mm. : 



FUNDULUS HETEROCLITIS. 



Age, 24 days. 



Number. Length. No. of cells. A v. No. cells. 



1 6 mm. 24 



2 6' mm. 27 



3 7 mm. 32 



4 7 mm. 35 



5 6.1 mm. 43 32 



Age, 17 days, varying in length from 5 mm. to 6V2 mm - 



Number. Length. No. of cells. Av. No. cells. 



1 5 mm. 32 



2 6 mm. 29 



3 6.', mm. 41 



4 6.1 mm. 45 37 



Age, 7 days, varying from. 3 to 4 mm. in length. 



Number. Length. No. of cells. Av. No. cells. 



1 3 mm. 30 



2 3.\ mm. 36 



3 4 mm. 40 



4 4 mm. 38 



5 3^ mm. 37 36 



EMBIOTOCA JACKSONI. 



Table showing the number of primitive germ cells in em- 

 bryos varying in size from 7.58 mm. to 3.25 mm. : 



