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accessory cells, but I do not believe this to be the case. I am 
certain that the ova do not originate from the peritoneal 
epithelium of the body-cavity diverticula, as Beard ('94) and 
others before him have claimed. 
A cross-section through the ovary of the right side of Fig. 19 is 
shown, as it appears under a higher magnification, in Fig. 21. 
Stage 8. 2.5—3.5 mm long. The body-cavity has reached 
its ultimate limits and is full of ova in all stages of growth. In 
this stage the »uterus« may be packed full of ripe ova ready to be 
discharged from the uterine orifice, which in this species is situated 
on the dorsal surface of the body near the cloacal opening. The 
testes, though reduced, are still voluminous; there are many mature 
spermatozoa, some of which have passed into the body-cavity, while 
others fili the vesiculae seminales. The ovaries are well developed, 
but I have found no karyokinetic figures to indicate a continued 
proliferation of oogonia. Doubtless triplet-cells still continue to be 
given off into the body-cavity, and probably this emigration of oocytes 
with their attendant cells may take place throughout the life of the 
animals either continually or intermittently. For obvious reasons this 
emigration is more difficult of demonstration than that which takes 
place when the body-cavity is still empty, or nearly empty. In 
this stage the animai is a functional hermaphrodite. 
Stage 9. 3.5 — 4 mm long. The body-cavity appears to be 
very large, because the ova which have distended it during their 
growth have been largely discharged into the water and the slower 
influx of ova from the ovaries is far from occupying as much 
space as the original batch. Most of the ova which are still found 
clinging to the peritoneal walls of the body-cavity are well along 
towards maturity. In this stage the animai is really a func- 
tional female, since the testes are nearly or quite exhausted. One 
often find a few ripe spermatozoa floating about in the body-cavity. It 
would seem that the animai does not live long after this stage which 
is attained by many individuals about the last of March. After this 
date I found very few mature individuals on the specimens of Ante- 
don which I examined. This matter, however, requires further in- 
vestigation at the hands of those who may have an opportunity of 
studying the species during the ensuing months of the spring and 
Summer. 
The series of stages of M. glahrum bere described will be found 
to differ in no important particular from the series of M. cirriferum 
