262 
W. M. Wheeler 
suspected by Lang who writes in bis text book ('88) concerning' tbe 
reproductive organs of Myzostomes (pag. 265) : »Bei den gesehlechts- 
reifen Thieren erfüllen zablreicbe Eizellen haufenweise das Parenchym 
zwischen den Darmästen, vorwiegend auf der Kückenseite. Diese 
Eimassen werden als Ovarien gedeutet. Es ist aber 
möglich, dass sie nur aus den von den wirklichen Eier- 
stöcken gelieferten Eiern bestehen. Die Herkunft und 
Bildungsstätte der Eier ist wenigstens noch nicht sicher 
erkannte« 
My attention was attracted to the ovaries while studying the 
oogenesis of M. glahrum. Starting out with the view of preceding 
authors I sought for the earliest stages of the ova in the peritoneal 
epithelium lining the body-cavity, but I failed completely to find any 
traces of proliferation or of karyokinetic figures in the cells of this 
layer — a failure which was all the more striking, because I had 
sectioned many young Myzostomes in which the ova were evidently 
rapidly increasing in number. It was duriug this search that I 
happened to find the two peculiar deeply staining masses of minute 
cells on either side of the intestine near the center of the body. 
These masses proved to be a pair of organs which Nansen ('85) 
alone of all previous observers had noticed. The Norwegian zoologist 
saw a single pair of these structures in M. giganteum and two pairs 
in M. graffi »on the dorsal side of the stomach«. He goes on to 
say that »these organs are situated in more or less open branches 
issuing from the uterus and consist of crowds of small cells with 
dark staining nuclei and nucleoli. I have fouud ova close to these 
organs. I consider these organs to be traces of the primordial 
ovaries which have, however, degenerated, the epithelium of the 
body-cavity acquiring the function of producing ova.« 
Nansen found these organs also in the »complemental males« 
of M, giganteum^ and carpenteri, This, he thinks, is no ob- 
jection to their being rudimental ovaries, since in these cases they 
lie in evaginations of what is obviously the rudimental uterus. The 
occurrence of these two rudiments is interpreted as a remnant of a 
former hermaphrodite condition. Nansen believes that he has seen 
egg-cells among the small cells of these organs, of which he gives 
no very accurate cytological description, but which he nevertheless 
represents correctly as they appear under a low power in bis plates 
1 The spacing is my own. 
