RELATION OF TRUE NUCLEOLUS TO LININ NETWORK. I2Q 



Development and Fate. The observations on the development 

 and disappearance of the plasmosome in Pselliodes seem to find 

 agreement in many other forms. The observations of Medes 

 ('04) on Scutigera and of Dederer ('07) on Philosamia are repre- 

 sentative types of this agreement. 



The latter part of the life history of the nucleolus, in which 

 this body is again assuming a granular texture, is suggestive of 

 that of Culex (Stevens '10), in which the achromatic body 

 absorbs chromatin substance extruded from the spireme during 

 the synizesis stage. Stevens bases her conclusion on the fact 

 that the body presents a series of colorations in the growth period. 

 She continues: "Whether the rejected material [from chromatin], 

 visible in some cases, is waste material or substances which have 

 some function connected with the growth stage of the germ cell, 

 we can only surmise." No doubt, Pselliodes presents better 

 material for a study of this point, as the foregoing observations 

 clearly show that this chromatin is used in the formation of the 

 first spermatocyte chromosomes (Figs. 26 to 30). 



The later stages in the life of the nucleolus, in Pselliodes, lead 

 to a suggestion as to its nature. It will be remembered that the 

 linin becomes attached to various parts of this spherical body. 

 The achromatic part then assumes a fibrillar but granular 

 appearance, and becomes indistinguishable from the linin. 

 These facts and observations, together with the recognized 

 nature and functions of the linin, lead me to suggest that the 

 plasmosome and linin not only possess similar characters, but are 

 one and the same material, the former being simply a globular mass 

 of the latter. 



Function. Since the achromatic part of the nucleolus of 

 Pselliodes seems to be a modified form of the linin, we should 

 expect a certain similarity in the functions of each. Further, 

 since the function of the linin is to support the chromatin during 

 the various stages of cell activity, we would attempt to ascribe 

 a similar function to the plasmosome. A brief review of the 

 preceding observations and illustrations clearly shows that we 

 are not disappointed in the attempt. In Pselliodes the behavior 

 of the sex-chromosomes and the achromatic material is identical 

 with the corresponding action of the chromatin and linin. The 



