288 CALKINS. [Vol. XI. 



may take place. Certainly in chromic and picric acid prepara- 

 tions the archoplasm masses are greatly reduced, and stain 

 much more intensely with miscellaneous stains than in other 

 cases. 



An accessory body {Nebenkeni) is often found in the develop- 

 ing germ cells of Lu^nbricus, usually in the spermatocytes of 

 the first order. This body also appears in the spermatic cells 

 of a great variety of forms where it is often mistaken for archo- 

 plasm. It was discovered by LaValette St. George ('67), and 

 has been repeatedly described by subsequent observers. Biitschli 

 ('7l) gave to this body, which he found in the spermatic cells 

 of insects and Crustacea, the name Nebenkern, a name which 

 has clung to it ever since. 



The term Nebenkern ("accessory nucleus") is unfortunate, 

 for in it there is nothing to designate any peculiarity or char- 

 acteristic of the body in question, and it might as well be 

 applied to any unusual structure of the cell. Such various 

 application has, indeed, been made. O. Hertwig ('75) used the 

 term Nebenkern to designate the micronucleus of the ciliates. 

 Nussbaum ('82) applied the same name to bodies constricted off 

 from the nucleus in cells of the hepato-pancreas, and Bloch- 

 mann ('84) gave the name ^^ Nebenkern " to the "yolk-nucleus," 

 a body found in the early stages of the developing ^g^ cells. 

 Many later writers have used the term in a more or less unde- 

 fined manner, until to-day the word Nebenkern has no especial 

 significance. 



In all of these cases, with the exception of Hertwig's applica- 

 tion of the term to infusoria, the name Nebenkern is unsuitable 

 and non-descriptive, for the structure so designated is not a 

 nucleus, although perhaps nuclear in origin. In the case of 

 the infusoria the structure called Nebenkern is much better 

 described by the term " micronucleus " which is now generally 

 adopted. The other bodies in the cell to which the name 

 Nebe?tkern is applied, notably in spermatic cells, in egg cells, 

 and in the glandular cells of the hepato-pancreas, are not 

 homologous with each other ; and the same term therefore 

 should not be used to designate them. In the spermatic cells 

 LaValette ('86), Platner ('86, '89) and Henking ('91) showed that 



