86 GEORGE T. HARGITT 



the supporting layer, though he could not demonstrate this. 

 Harm ('02) makes the same claim and also believes the germ cells 

 are present in the larva (planula) and can there be distinguished 

 from other cells. This latter claim is an important one if it can 

 be substantiated, since it would seem to show an extremely early 

 differentiation of the germ cells C. W. Hargitt ('06) in the 

 American species C. leptostyla, finds the egg cells always distin- 

 guishable in the entoderm and never originating in the ectoderm. 

 Goette ('07) finds the germ cells to arise in C. multicornis "only 

 from transformed half-entoderm cells." 



There is no doubt that the egg cells are usually found, and very 

 easily distinguished as germ cells, in the entoderm against the 

 supporting layer. Figures 3 to 5 show various stages of growth 

 of the eggs in this position. Concerning the origin Weismann 

 claimed the ectoderm on theoretical grounds, his observations 

 not including any demonstrated cases of eggs in the ectoderm. 

 Harm, on the contrary, gives figures of cells in the ectoderm and 

 others in the supporting layer and entoderm of the planula which 

 he says are egg cells. Unfortunately his figures are too small 

 to enable one to determine the characteristics of these cells. His 

 description states only that such cells have a more compact 

 cytoplasm than the adjacent cells. 



In figure 1 is represented a cell found in the ectoderm of the 

 polyp against the supporting layer, and figure 2 shows two 

 similar cells within the supporting layer but not quite separated 

 from the ectoderm. These cells are quite similar to the small 

 oocytes shown in figures 3 and 4 in the entoderm. Such cells 

 found in the entoderm can be directly connected, stage by stage, 

 with large egg cells and there is no question of their character; 

 consequently similar cells found in the ectoderm must also be 

 considered as primordial egg cells. As a result there is repre- 

 sented in the material on which this study is based evidence of 

 the origin of some of the egg cells in the ectoderm and their 

 probable migration (fig. 2) through the supporting layer into the 

 entoderm. However, in a great many sections of numerous 

 individuals obtained from two regions (Woods Hole, Massa- 

 chusetts and Casco Bay, Maine) this was the only one in which 



