The Sexual Phases of Myzostoma. 
261 
V. GtRAFf’s ratlier guarded remarks on these species in the paper to 
whicii Beard evidently refers f84a). 
Beard's Interpretation of the small individuals as »complemental 
males« was accepted by Nansen ('85), who succeeded in finding them 
also in the thred species which he studied. Nansen, however, 
dissents from Beard’s general conclusion regarding the origin of 
hermaphroditism in the Metazoa. 
In a short paper of recent date ('92) Prouho undertook to show 
that the small individuals attached to the large hermaphrodite spe- 
cimens of M. alatum are really young hermaphrodites in which the 
female Organs have not yet developed, and he goes on to say: «Je 
n’ai pas encore la preuve que les mäles complementaires du M. glahrum 
acquierent, eux aussi, des ovaires, mais ce que j’ai observe chez le 
M. alatum me porte ä le croire.« From his observations on M. 
puUinar he concluded that this species is dioecious. He tabulates 
the Meditemnean species of Myzostom,a thus: 
»Type hermaphrodite M. cirriferum 
» » proterandre M. alatum 
» )) avec male complementaire (?) M. glahrum 
» dioique avec male pygme M, pulvinara. 
Such startling sexual variations occurring within the limits of 
a single genus can lead to only one of two reflexions: either we 
must have here a very unusual instability of sex, or there must be 
something radically wrong about the accepted accounts of Myzostome 
anatomy. Most authors have tacitly accepted the former alternative 
and have placed too implicit confidence in their interpretation of the 
reproductive organs. A more careful study of these organs, especially 
of the female organs, puts the whole question in a different light. 
All preceding authors have been led astray by regarding the general 
peritoneal epithelium or general parenchyma as giving rise to the 
ova, whereas these elements are produced only by a very restricted 
portion of the peritoneal epithelium, which may be readily compared 
with the ovaries of Annelids, Vertebrates, etc. Even recent authors 
like Beard and Prouho would probably agree with Braun who, in 
a resume of the work done on Myzostomes up to 1888, defines the 
ovaries thus (pag. 213): »Die Ovarien stellen 7 — 8 Paar verästelte, 
zwischen den Darmblindsäckchen und Hoden gelegene Schläuche dar, 
die sich manchmal bis zum Scheibenrand erstrecken und alle seitlich 
an einem gemeinschaftlichen, median verlaufenden, weiten Canal an- 
sitzen, dem Uterus.« The true condition of affairs must have been 
18 * 
