100 V. E. EMMEL 



strate such granules in the granular leucocytes of even the adult 

 cat and that consequently failure to demonstrate these granules 

 in the embryonic cells does not constitute evidence of a neces- 

 sarily negative character. With reference to this point, how- 

 ever, it may be noted that the eosinophihc, non-granular cells 

 in question are not hmited to the embryo of the cat for appar- 

 ently the same cells can be also demonstrated in the embryonic 

 mesenchyma of the rabbit, mouse and pig, mammals in the adults 

 of which a corresponding difficulty in staining the granules in 

 the granular leucocytes cannot be said to be encountered. Sec- 

 ond it can be demonstrated that degenerating erythroblasts, 

 occasionally found in the embryonic circulation may undergo 

 cytological changes apparently identical with the structural 

 characteristics to be found in the mesenchymal cells in question. 

 Erythrocytic nuclei as is well known, may become very irregular 

 in shape: bilobed or even constricted into several subdivisions. 

 Early stages in such nuclear changes are indicated in figure 37 

 and reference has already been made to Weidenreich's account 

 on this subject (p. 595). In man lobulation of erythrocytic 

 nuclei has also been described under pathological conditions in 

 the circulation of the adult (Jiinger, '00, p. 109). Maximow 

 ('09, p. 478) also recognizes the occurrence of such nuclear lob- 

 ulation even in the embryonic circulation but described the 

 nuclei in such instances as becoming smaller, more compact and 

 taking a darker stain. It may be questioned, however, whether 

 this is necessarily always the case. For even in the circulating 

 blood, degenerating erythroblasts may be observed with lobu- 

 lated nuclei which cannot be said to present an especially more 

 compact structure (fig. 37). A similar comparison can be made 

 in figure 33 of Maximow's work in which lobulated erythrocytic 

 nuclei are shown which do not appear either essentially darker 

 in stain nor more compact in structure than the unchanged nu- 

 clei of the adjacent erythroblasts or the nuclei of the co-called 

 leucocytes in figure 27 of his monograph. As for the relative 

 size of the cells no conclusive distinction can be clearly drawn 

 on this basis between the cells in question in the mesenchyma 



