No; 2:] ANURIDA MARITIMA. 245 
the ovum. It is true that no traces have been seen in the 
ovum itself, but the position close to the nucleus of the nutri- 
tive cells at the time just previous to yolk formation and its 
subsequent disappearance are all indications of its homology 
with the “yolk nucleus” of the second class. 
Among the myriapods this body has been extensively ob- 
served. Balbiani ('83) and Zograff ('90) both report a yolk 
nucleus present in the small ova of the chilognath Geophilus. 
Balbiani figures and describes it as originating from the nucleus 
and in part forming follicle cells and in part the undoubted 
yolk nucleus, which in this case in its greatest develop- 
ment has a radiate structure suggesting the aster of cleavage 
spindles. It disappears while the ova are still very young. 
Heathcote observes the absence of a complex yolk nucleus in 
Julus such as was described for Geophilus. Lubbock (61), de- 
scribing the eggs of Julus, notes the absence of the vitelligenous 
bodies described for Glomeris, but notes the presence of a small 
body in eggs of an intermediate size that he compares to the 
laminated body of spiders’ eggs; evidently it is a yolk nucleus. 
It is absent in smaller and larger eggs. Lubbock describes 
vitelligenous bodies as present in the egg follicles of Glomeris, 
but distinguishes them from yolk nuclei. Stuhlmann (86), 
however, figures part of the ovary of Glomeris in which yolk 
nuclei are evidently present, and, from his descriptions and 
figures, more closely resemble those found in Anurida than any 
others hitherto described. Kenyon ('95) describes a small body 
near the nucleus in the young ova of Pauropus which disappears 
in older stages to be followed by yolk spherules, which is evi- 
dently the same structure, although not called so by him. 
Schmidt ('95) describes in Scolopendrella a small body inside 
of the egg cell staining as deeply as the nucleus, which he calls 
a migrated follicle cell, but which is quite possibly the yolk 
nucleus. Stuhlmann ('g6) figures a large yolk nucleus present 
in the ova of Peripatus edwardsii which, strangely enough, per- 
sists late in the egg’s history, even after fertilization. It is 
not necessary to enumerate any more forms of animals in which 
this structure appears; it can be said to occur among the re- 
maining invertebrates and the vertebrates, with many variations 
