652 D. B. CASTEEL 



either applied to the nuclear wall or in its immediate neighbor- 

 hood, and they are later more widely scattered in the cytoplasm. 

 A glance at figures 4 to 8 will show the positions occupied by 

 these bodies. Before the time of maturation they entirely dis- 

 appear. From the morphological standpoint the evidence is 

 very conclusive that these bodies arise in the nucleus, pass to 

 its periphery, reach the nuclear membrane, and in some form 

 and in some manner pass through the wall, later to become 

 free in the cytoplasm. The passage of these substances through 

 the wall has not been observed, but in several cases the nuclear 

 wall is bent outward in front of the body and somewhat modified 

 in texture, but these conditions may represent artefacts. 



Regarding the nature of these bodies the following suggestions 

 are offered. They do not represent the 'extranuclear chromatin' 

 of Schaxel ('11) and others, for their staining reactions do not 

 suggest chromatin, nor are they similar to the pseudochromatin 

 granules of Beckwith ('14) either in point of origin or in micro- 

 chemical reactions. In many particulars these bodies recall the 

 nuclear globules of Beckwith, for they bear like positional rela- 

 tionships, react similarly to Benda's stain and, after a brief 

 existence, they disappear from the cytoplasm. They are not 

 mitochondria and appear to bear no definite relation to the mito- 

 chondria, for acid fixatives such as Carnoy's fluid have no effect 

 upon them, while dissolving all of the mitochondria in the cell. 

 Moreover, the mitochondria are already present in the cell when 

 these bodies appear. The extra-nuclear bodies are present in 

 the cytoplasm when the first rudiments of the vesicular bodies 

 are becoming visible, but they are not transformed into these 

 latter structures, for the vesicles are also dissolved by strong 

 acetic solutions; nor is there any morphological evidence of such 

 a transformation. That the presence of extra-nuclear bodies in 

 the cytoplasm gives the chemical stimulus necessary for the 

 formation of the vesicular bodies, is possible but scarcely 

 probable. 



The cellular structure with which the extra-nuclear bodies 

 appear to be most closely related in microchemical reactions is 

 the true nucleolus or plasmosome. After Benda's stain the 



