40J: Wm. s. Marshall and C. T. Vorhies, 



nucleolar material in our preparations is in general evenly distributed 

 and we find no areas, of any considerable size, from which it is absent 

 (Korschelt [10]). 



ComiKirison of normal tvith active glands. — Brown sand covers 

 the bottom of the springs in which the larvae of Flatyjjhylax live, 

 which, if used in our aquaria, made it impossible to determine if new 

 material had been added to the cases. We therefore placed in the 

 aquaria crushed red sand-stone; this the larvae used in building their 

 cases and the contrast in color enabled us to determine at once if 

 work had been done. 



We describe as normal those spinning glands taken from larvae 

 which had not for several days been making use of them. The larvae 

 fiom which these normal glands were taken were always those which 

 we had kept in our aquaria and therefore were not normal in one 

 respect, i. e., they did not come directly from their natural habitat. 

 We were sure that the larvae we took as normal had not for several 

 days added any new sand grains to their cases, but, as to the use 

 of the spinning glands for other purposes, if any, we could not say. 

 An examination of the glands taken from several of these normal 

 larvae showed but very slight differences, and, after an examination 

 of all the sections, one was selected as a type of the gland. As a 

 matter of fact any one of the series of sections might have been selec- 

 ted, all being very similar and yet showing a difference from the 

 glands which had been active for even a few hours. 



The work on the minute structure of the spinning glands of in- 

 sects has been mostly done on the larvae of the Lepidoptera, and it 

 all shows a great similarity to what we have found in the Phryga- 

 nidae. In general the appearance of two deeply staining portions 

 within the nucleus has been noticed; Korschelt [10] called these the 

 macrosomes and microsomes and held that one always stained lighter 

 than the other. Meves [16] claimed that the macrosomes are the 

 nucléoles (Pyrenin) and the microsomes the chromatin or nuclein of 

 the cell. According to Korschelt [10] the macrosomes appear as large 

 round, irregularly angular, or spindle-shaped bodies, which are, in 

 many nuclei, of nearly the same size, but in others show great variation 



