728 CALKINS. [Vol. XV. 



('96), V. Erlanger ('97), etc.) Others, however, while regarding 

 the sphere as a differentiation of the cytoplasmic reticulum, 

 find that it is permanent in the cell, dividing by fission like 

 the centrosome. (Van Beneden '87, Meves '95, vom Rath 

 '95.) Here the two views stand rather close together ; on 

 the one hand, it is maintained that there is a distinct structure 

 permanent in the cell, but composed of modified cytoplasmic 

 reticulum ; on the other hand, it is held that the distinct struc- 

 ture is composed of a distinct substance. The difference here 

 is certainly not great. ^ 



The fact that in some cases the sphere appears only during 

 mitosis is perhaps the most serious obstacle to Boveri's inter- 

 pretation. He avoids it, however, by maintaining ('96) that 

 the archoplasm is not necessarily restricted to a definite body, 

 but may exist throughout the cell in the form of minute 

 granules, which during mitosis are attracted around the centro- 

 somes, forming spheres. He now ('97) considers that the eggs 

 of Ascaris, upon which his idea was based, differ from other 

 cells in regard to the presence and form of the archoplasm, 

 the general rule being that fibers run directly from the centro- 

 some into the cytoplasm. He also says that with the excep- 

 tion of Noctiluca (Ishikawa) he knows of no other form of 

 cell where a solid archoplasmic substance exists around the 

 centrosome.^ 



Schaudinn's Paraniocba must now be included with Nocti- 

 luca. Kostanecki's ('96) work on Ascaris does not sustain 

 Boveri's conception, since he finds that, as in other forms, the 

 spindle-fibers pass directly from the centrosome into the cyto- 

 plasm ; and his work shows that in regard to archoplasm this 

 form cannot be classed with Noctiluca and Paraniocba. 



' In a number of cases the term " archoplasm " has been used to designate 

 portions of the cell which are not obviously homologous with the parts described 

 by Boveri. Thus Foot ('96) calls everything in the cell which stains with Lyons 

 blue " archoplasm," and Moore ('94) apparently restricts the term to the residual 

 spindle-fibers (Nebenkem). 



^ " Ja, mit Ausnahme von Noctiluca, wo das Archoplasma nach Ishikawa 

 genau den Eindruck jener kornigen Substanz des Ascaris-^xts macht, wiisste 

 ich keinen anderen Fall zu nennen, wo zunachst im Umkreis des Centrosoms 

 eine dichte kornige Kugel besteht, die sich allmiihlich in das Strahlensystem 

 umwandelt " (/. c, p. 40). 



