CELLULAR ELEMENTS OF THE MAMMALIAN EMBRYO 89 



stained structures. Some of the bodies may be much paler than 

 others, but the sharply defined basophihc rim which can still be 

 observed in many cases seems to render them structurally dif- 

 ferent from the hyalin bodies derived from lymphocytes and 

 mononuclear cells. 



While the present data is consequently negative as to the 

 derivation of these eosinophiUc bodies from the cytoplasm of 

 either erythrocytes or macrophags, it does, however, furnish 

 evidence of a more positive character as to another conclusion 

 concerning their origin. Concerning the basophilic material 

 already described it appears significant to note that aside from 

 the form of a narrrow peripheral ring it may present pronounced 

 additional accumulations in the form of either irregular masses 

 (figs. 22, 23), one or more delicate crescentic masses (fig. 21) 

 or small, compact and more or less centrally situated spherules 

 (figs. 25, 26). In studying erythrocytic nuclei (p. 597) condi- 

 tions are met with which are strongly suggestive with reference 

 to the present question. Not infrequently both free and in- 

 gested erythrocytic nuclei are observed undergoing changes in 

 which instead of becoming more or less compact in a single 

 pyknotic body or broken up into several compact nuclear frag- 

 ments the nucleus becomes lighter colored at its center and has 

 a dark staining periphery (figs. 34 and 36). In such cases it 

 appears that the dissolution or chemical modification of the 

 chromatin proceeds from the center towards the periphery in 

 such a manner that a stage may be reached in which the baso- 

 philic staining material remains as only a very thin peripheral 

 envelope, the interior of which may take an eosin stain of such 

 a character as to render it practically indistinguishable from the 

 hemoglobin containing cytoplasm of an erythrocyte. Jolly 

 ('07, p. 245) has further shown that under certain circumstances 

 these changes may proceed to a complete tinctorial transforma- 

 tion of the entire chromatin content to oxychromatic staining 

 material. The close approximation of the cytological appear- 

 ance of such highly modified nuclei to that of the eosin staining 

 bodies in the coelomic cavities appears to justify the conclusion 

 that the latter are also of a similar character. Concerning the 



