GERM CELLS IN TATUSIA NOVEMCINCTA 



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carried along in the lateral surfaces of the primitive intestine. 

 There seems to be no evidence whatsoever, in the armadillo, 

 of germ cells ever entering into the mesoderm or its forming blood 

 vessels, as described by Swift in the chick. Since Swift's work 

 is not only able but convincing, it merely remains to be said 

 that the paths of migration in birds and in this mammal differ. 

 It seems certain that the germ cells of the armadillo, passing 



Text fig. B A reconstruction of specimen 290 (taken from Patterson, '13), 

 showing the location of germ cells at this period. The dotted lines indicate the 

 plane of the sections, in which germ cells were found at points (x). 



along the blastocyst entoderm into the embryonic entoderm, 

 become immediately incorporated in the intestinal wall without 

 ever being seen to pass through the mesoderm at all. Of course 

 this is no new thing in mammalian work, since Fuss ('12) and 

 Rubaschkin ('08) have described similar conditions in the 

 rabbit and pig. My observations seem merely to confirm those 

 of Fuss on this point. 



From the time of the late primitive streak up until a stage 

 where the embryo shows a well-developed cervical flexure (figs. 

 6a, 7a, 8a), the germ cells remain in the intestinal entoderm. 



