Zool— Vol. I.] EISEN—PLASMOCYTES. 5 1 



nature of this amoeboid body is proved to be correct by 

 future investigation, then we shall have here the third known 

 instance of a free and independent archosome, the other two 

 being the plasmocyte in the blood, and the wormlike sperma- 

 tozoon of Physa. 



If we now consider the budding of the centrosomes as 

 shown by Heidenhain, and that of the plasmocyte as shown 

 by me, does it not demonstrate that the centrosphere and 

 centrosomes are in reality distinct and independent elements, 

 though as yet we cannot in all cases know them to be in- 

 dependent of each other? Does it not appear also possi- 

 ble that these two structures once existed separately but 

 later on joined in a symbiotic existence, long before the 

 archosome as a whole had joined the caryosome and cyto- 

 some to make up the present cell? 



Identification of the Spheres. — I believe it will prove of 

 interest to attempt an identification of the cytoplasmic zones 

 of the plasmocytes and plasmocytoblasts with those observed 

 in perfect cells. Such identification is for several reasons 

 bv no means easy. Many investigators have not named the 

 respective cytoplasmic zones observed by them, and, in 

 cases where names have been given, they have frequently 

 used descriptions or descriptive names which are not trans- 

 latable from one language to the other. Another obstacle 

 is found in the different stains used to differentiate the 

 respective zones. The various fixatives which are supposed 

 to preserve the elements of the cell in their original appear- 

 ance undoubtedly frequently accomplish the very opposite, 

 at least with certain parts. Every cytologist knows only too 

 well how differently the stains act after different fixatives 

 have been employed. I will not dwell particularly upon the 

 advantages of the methods I have employed in my investi- 

 gations in this case, but will observe only this, that whatever 

 changes the cytoplasmic zones may have undergone, they 

 are not resultant from the use of violent chemicals. 



There is no reason to suppose that we should find 

 a similar grouping of cytoplasm in every cell, even when 

 the cells belong to the same cell species, but in related 



