Zool— Vol. I.] EISEN—PLASMOCYTES. 27 



and lies prominently in the white centrosphere, while on the 

 other hand it encloses two small, separated centrosomes. 

 In fig. 38^ the somosphere appears to be absent, the centro- 

 somes standing out free in the centrosphere. In fig. 49, 

 which is in many respects a very instructive one, the somo- 

 sphere is stained dark blue and starlike in form, inclosing 

 some centrosomes of rather uncertain shape. In the early 

 plasmocytoblast the centrosomes always lie very close to- 

 gether, and can only with difficulty be segregated; but as the 

 spheres grow the centrosomes separate, each carrying with 

 it some part of one of the inner spheres. I have never 

 found more than four centrosomes together in one plas- 

 mocytoblast, and generally their number does not exceed 

 three. In the plasmocytoblasts the somosphere and centro- 

 somes are too small to be readily studied, the larger plasmo- 

 cytes offering much better facilities in this respect. 



The relationship of the three inner spheres — those of the 

 microcentrum — is not by far cleared up, but it seems that the 

 somosphere and centrosomes are much more intimately con- 

 nected than the centrosphere and the somosphere. 



IX. Different Kinds of Protoplasm. 



The distinct differentiation possessed by the various zones 

 naturally indicates that the protoplasm composing them con- 

 sists of at least as many different kinds as there are zones. 

 The word cytoplasm, as referable to all protoplasm con- 

 tained in the cell outside of the nucleus, would thus not 

 express and define the various kinds of protoplasm found 

 in the inner spheres. If we, for convenience sake and with 

 reason of a physiological difference, speak of cytoplasm as 

 distinct from caryoplasm, we can, with equal propriety and 

 for greater distinctness, refer to the protoplasm of the 

 archosome as being distinct from that of the cell and the 

 nucleus. That the spheres of the archosome must be 

 considered as quite distinct from those of the cell and 

 the nucleus is quite evident from what I have mentioned 

 above, and, moreover, they must be considered as a whole 



