Zool.— Vol. I.] EISEN—PLASMOCYTES. 1 7 



appears to be in the center of the plasmocytoblast. In the 

 former, the different cytoplasmic layers superpose each 

 other like a series of hollow cones placed one on the top of 

 the other on a level plane, with the centrosomes almost 

 resting on this plane. In the other, or spherical form of 

 plasmocytoblasts, the cytoplasmic layers surround each other 

 as the hulls of seeds. There is here no broad base, but a 

 number of concentric layers of different density, color, and 

 structure. In a general way these zones correspond to the 

 ectoplasm and to the microcentrum (somosphere with cen- 

 trosomes) of some investigators, but as great confusion ex- 

 ists as to names I have considered it best to name each zone 

 or sphere separately, as follows, counting from the exterior 

 to the interior, or from the top to the base: — 



A. Cytosome, or cytosomal spheres, ectoplasmatic 

 spheres; spheres not part of the nucleus and archoplasm — 



i. Plasmosphere. 



2. Hyalosphere. 



3. Granosphere. 



B. Archosome, microcentrum, archoplasmic spheres, 

 archoplasm with centrosomes; spheres not part of the 

 nucleus or cytosome — 



4. Centrosphere. 



5. Somosphere. 



6. Centrosome. 



As will be seen, and as I expect to demonstrate in the fol- 

 lowing pages, the three outer spheres are purely cytoplasmic 

 spheres, parts of the cell proper, for which, as a whole, I 

 propose to retain the name cytosome, in juxtaposition to the 

 caryosome, or nucleus, or to the three inner spheres, for which, 

 as being of an entirely different nature, I propose the name 

 archosome. This latter corresponds, at least in part, to 

 Heidenhain's microcentrum, and to the archoplasm with 

 centrosomes of some investigators. 



The two following diagrams will illustrate this better. 

 The first one gives the shape of the conelike plasmocyto- 



