GERM CELLS IN TATUSIA NOVEMCINCTA 347 



situated between the ectodermic and entodermic layers of the 

 blastocyst at points where the layers are fairly widely separated 

 (fig. 1 and la) It is decidedly more diflftcult to locate germ 

 cells at this time than in later stages, since the neighboring 

 cells are naturally larger now than they are later. 



Next in order is the primary bud stage represented in speci- 

 men 247 (fig. 2a). Here the germ cells are similarly located. 

 Text figure 1 represents a reconstruction of no. 247, point X 

 indicating the location of the germ cells observed in this stage. 



Text fig. A A reconstruction of 247, point x indicating the location of the 

 germ cells at this stage. (This figure is taken from Patterson, '13.) It will 

 be noted that the germ cells are not found in this specimen in the primary bud 

 regions. 



It will be noted that they appear outside of the points where the 

 primary buds are forming. No germ cells were found in the 

 vicinity of the primary buds. There is not a sufficient number 

 of primary bud stages in my possession to permit of stating defi- 

 nitely the location of these cells on the blastocyst at this time, 

 but I am inclined to believe that they probably lie Scattered 

 very sparsely here and there in the entoderm, chiefly, it would 

 seem, in the regions which do not give rise to the primary buds. 

 What signifiance this fact may have, it is hard to explain. I 

 question whether these few stray cells, found in stages before 

 the embryos appear, play much part in the subsequent history. 

 To definitely settle the matter of location, careful examinations 

 of a number of primary bud stages is indispensable. In figure 



