Cytological studies on the spinning glands of Platyphylax etc. 413 



in them are in the cytoplasm. A section through a gland taken from 

 a young pupa (Fig. 22) shows the nucleus to contain a few small 

 irregular nucléoles of a bright safranin color and numerous chromatin 

 granules which have not been deeply stained violet, but otherwise 

 appear the same as in the different nuclei we have described. 



The other contents of the cells show a decided change, the entire 

 gland being filled whit globules of varying sizes. These are largest 

 near the inner surface of the gland, decreasing in size as they approach 

 the outer boundary; more small ones are in the inner than in the 

 outer half of each cell. The globules are mostly circular in outline, 

 although many of a slightly irregular form are seen. They do not 

 darken with the osmic acid of Flemming's solution and are colored 

 safranin by the triple stain; their color is lighter and not nearly so 

 dense as that of the nucléoles. 



Notes on secretion in the glands. — Glands which are normal 

 or have been active for short periods only, are entirely filled with the 

 mass which they secrete, but those which have been active for some 

 time show this mass to occupy but a part of the lumen of the gland. 

 In those sections on which the triple stain was used the secretion, 

 which shows a finely granular structure in all the preparations, is 

 colored a dark violet. Some few slides show the secretion without 

 any vacuoles, others with a few irregularly scattered ones but a large 

 majority of our preparations showed the following arrangement. A large 

 number of vacuoles, fairly, regular in size were close together and 

 formed a continuous layer, tubular in shape: in longitudinal sections 

 these always appeared in two rows parallel to the surface of the gland 

 (Fig. 23), in some nearer the surface than in others; in a trans vei se 

 section the vacuoles formed a circle. Specimens in whi'ch the vacuoles 

 showed this regular arrangement nearly always contained others which 

 were scattered irregularly throughout the secretion, the majority, 

 however, being in the central part and enclosed by those which were 

 regularly arranged. 



The following short account describes the conditions found along 

 the inner surface of the gland and the outer of the mass of secretion, 

 including whatever was found between these two areas. At this place 



