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