MARCH: GERM CELLS OF CORYMORPHA. 255 



delayed. There is apparently no constant difference between 

 the sexes as to this question of migration, nor with regard to 

 the number of primitive germ cells in the early stages. 



Table II. — Number of Germ Cells in Stage B Buds. 



, Entoderm. ■ — s Total 



Bud. Sex. Prox. Cent. Distal. entoderm. Ectoderm. Total. 



1 Male 7 17 4 28 1 29 



2 ? 4 8 5 17 5 22 



3 Male 12 9 1 22 7 29 



4 Female 7 8 2 17 6 23 



Table II gives the number of germ cells in stage B. In this 

 stage there is an increase in the number of germ cells in the 

 entoderm, accompanied by a corresponding decrease in the 

 number of germ cells in the ectoderm of the bud, without any 

 decided change in the total number as compared with the total 

 number in the previous stage. 



Table III. — Number of Germ Cells in Stage C Buds. 



, Entoderm. . Total 



Bud. Sex. Prox. Cent. Distal. entoderm. Ectoderm. Total. 



1 ? 7 14 .. 21 1 22 



2 ? 3 7 5 15 2 17 



3 Female 4 7 3 14 4 18 



4 Male 5 11 . . 16 3 19 



5 Male 8 11 1 20 6 26 



Table III shows the number of germ cells in the medusae at 

 stage C, the time of the formation of the "glockenkern." 

 There is no great change in the total number of germ cells, 

 but the arrangement is somewhat different. The reduction in 

 the number of germ cells in the ectoderm shows that they are 

 still passing from ectoderm to entoderm, without being re- 

 placed by other germ cells from the adjacent ectoderm of the 

 peduncle. The continued predominance of germ cells in the 

 central third of the entoderm, and in increase in the number 

 in the distal third, indicates a constant migration toward the 

 glockenkern" at the apex. 



>> 



Table IV. — Number of Germ Cells in Stage D Buds. 



, Entoderm. — - — ,, Total "Glocken- 



Bud. Sex. Prox. Cent. Dist. entoderm. Ectoderm. kern." Total. 



1 ? 6 11 1 18 3 4 25 



2 Female 2 3 3 8 . . 11 19 



3 Female 8 13 3 24 1 . . 25 



4 Female 3 10 7 20 2 . . 22 



5 Female 3 7 3 13 1 7 21 



In stage D (table IV) some germ cells have passed into the 

 "glockenkern," and the germ cells have practically disap- 



