Cytological studies on the spinning glands of Platyphylax etc. 401 



of small spherical or oblong nuclei on either side of the gland, with a 

 clear space between, in which lies the lumen. Helm [6] and Carnoy [1] 

 have flgared nuclei of a similar appearance from the young stages of 

 Lepidopterous glands. The difficulty of splitting this slender anterior 

 portion of the gland makes a complete series of nuclei from this part 

 hard to obtain, but a study of whole mounts shows that the complexity 

 of the nuclei changes, as we pass toward the glandular part, more 

 rapidly than does the size of the cells. The next stage figured (Fig. 8) 

 is taken from a point some distance back of the anterior end. It will 

 be noticed that, while in one or two places the branches of this and 

 other nuclei lie very close together, they do not join, but a space can 

 be readily determined between them. The figures given by Helm [6] 

 and Carnoy [1] show, even in some very simple nuclei, the branches 

 anastomosing to form a network with enclosed areas of cytoplasm. In 

 Platyphylax designatus the nuclei afford negative rather than positive, 

 evidence of anastomoses between the branches, all such apparent unions 

 having been carefully studied for the purpose« of determining whether 

 actual confluence was present. In this last figure may be seen an 

 example of the tendency, which many nuclei have, to be drawn out, 

 at some points, into slender threads. 



Figure 2 shows the nucleus of a cell which, from its size, might 

 come from either end of the gland, both these parts being smaller 

 than the central portion. This nucleus may be said to have a common 

 center with three radiating branches, each of which again divides into 

 two portions. This radial arrangement of the nucleus is also noticeable 

 in Figs. 4 and 5, but in these two figures the center of branching will 

 be seen to be excentric and we have found that such a nucleus is of 

 a special type and not common is Platyphylax. Some authors, however, 

 show the nuclei with a distinct center on which the branches are ra- 

 dially disposed. Henneguy \7\ 



À more complex nucleus, which does not, however, occupy a large 

 amount of space within the cell, is next shown (Fig. 4). A fairly dis- 

 tinct center with radiating branches may be seen at one end of the 

 cell. A portion of this nucleus appears at first to be separated from 

 the rest (Fig. 4, a), but a close examination shows it to be attached by 



Internationale Monatsschrift f. Anat. u. Phys. XXllI. 26 



