90 V. E. EMMEL 



occurrence of such degenerating erythrocytic nuclei in the 

 coelomic cavity two possible sources of origin may be noted: 

 first, through the disintegration of the erythroblasts occurring 

 in the coelom itself as will be presently described, and second, 

 through the occasional passage or elimination into the coelomic 

 cavities of the degenerating erythrocytic nuclei frequently found 

 in various regions of the coelomic walls. The latter possibility 

 would be in accord with the fact that these eosin staining bodies, 

 as already. noted, are frequently found in intimate contact with 

 the surface of the coelomic walls. 



2.. Nucleated erythrocytic cells 



Figure 18 illustrates the second sub-group of coelomic cellular 

 elements. In contrast to the coelomic macrophags, these cells 

 have an eosinophilic instead of a basophilic cytoplasm. The nu- 

 cleus also may be more irregular in form, lobulated or even sub- 

 divided into two or more almost wholly if not entirely separated 

 segments (fig. 19). The cytoplasm is frequently vacuolated. 

 The cell as a whole may be either round or more irregular in 

 shape with the peripheral cytoplasm presenting a fragmented 

 appearance. In the material studied such cells were most fre- 

 quently observed in rabbit embryos although they were also 

 present in both mouse and pig embryos. They may occur as 

 isolated elements or in groups consisting of two or three to a 

 dozen cells. 



Upon first examination the polymorphonuclear character of 

 some of these cells is suggestive of leucocytic elements. On the 

 other hand in no instance was there any special leucocytic gran- 

 ulation detected. On the contrary the cytoplasm is of a homo- 

 geneous structure and in many instances (figs. 18, 19) the stain- 

 ing reaction of both cytoplasm and nucleus is apparently iden- 

 tical with that of the typical erythrocytes in the same embryo. 

 Concerning the origin of these cells the possibility was consid- 

 ered as to their representing a partial or abortive tendency 

 toward erythrocytic differentiation on the part of the coelomic 

 macrophags. There can be no question but that such cells as 



