THE DEVELOPMENT OF THE NUCLEI OF THE 

 SPINNING-GLAND CELLS OF PLATY- 

 PHYLAX DESIGNATUS WALKER 

 (TRICHOPTERON). 



C. T. VORHIES. 



The large and complexly branched nuclei of the spinning- 

 gland cells of trichoptera (and lepidoptera) contain two kinds of 

 stainable material. That one kind of this material is chromatin 

 there is no doubt ; that the other is nucleolar material perhaps 

 the majority of cytologists now believe, but there have been 

 some differences of opinion concerning this point. These mate- 

 rials in the glands of trichoptera — at least in P. designatus and 

 some other species — consist of larger, irregularly shaped 

 masses, and small, more evenly sized granules, which have a 

 roughened appearance as if made up of smaller particles. In 

 the lepidopteron, Isia Isabella, the two materials are scarcely dis- 

 tinguishable by the size of particles, but only by their staining 

 reactions. The smaller granules stain blue in the triple stain 

 of Flemming, while the larger take the red stain characteristic 

 of nucleolar material. These larger particles will be hereinafter 

 referred to as nucleoles or nucleolar material. 



A brief review of the literature of this subject seems desirable. 



Helm (1876), though he indicates the ontogenetic changes of 

 form of the nuclei, does not distinguish the contents of the same. 



Carnoy (1884), in a rather diagrammatic drawing (Fig. 54) of 

 a spinning-gland cell from the larva of a trichopter, shows fila- 

 ments of " nucleine " which undoubtedly represent the nucleolar 

 material. He does not distinguish the chromatin in this draw- 

 ing. In Figs. 78 and 79 he shows a portion of a branched 

 nucleus from the gland of a moth larva, and a cell from the 

 gland of the larva of a microlepidopter. In both of these, the 

 nucleolar material and chromatin are indicated, but the chromatin 

 is not mentioned and the nucleolar material is designated as the 

 " boyau nucleinien." This skein of nuclein he believes to be 



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