The Sexual Phases of Myzostoma. 
263 
(Tab. 2 Figs. 6, 15 and Tab. 9 Fig. 23). In the description of the 
figures they are called »problematic Organs», and tbere are many 
indications both in the Danish and English text to show that he 
was far from haviog reached a definite conclusion respecting the 
striicture and function of these organs. 
Sections of well preserved specimens of M. glabrum convinced 
me that Nansen’s »problematic organs« were in no respect rudi- 
mental, and the identity of the triplet-cells, of which the organs 
consist, with the youngest stages of the ova in the body-cavity soon 
led to their interpretation as the only tnie ovaries of the Myzostome ; 
a conclusion fully borne out by a subsequent study of their origin 
from local proliferations of the peritoneal epithelium and the not 
uncommon occurrence of karyokinetic figures in their. cells (proli- 
ferating oogonia). 
In 1895 I published a brief preliminary account of my work 
on the Mediterranean species and showed how the discovery of the 
true ovaries supplied the very point needed to reduce the apparently 
complicated and heterogeneous relations of the sexes to a condition 
of hermaphroditism uniform throughout the Myzostome group but 
with a varying prominence of the protandric and hysterogynous 
stages. Although I had made no observations on the cysticolous 
species I ventured to extend my conclusions to these forms, since 
the sexual phases of the entoparasitic species M. pulvinar^ which 
agrees closely with the extreme Cysticola, seemed to be capable of 
the same interpretation as those of the free-living species. That 
this extension was sufficiently justified, is proved by the observations 
on M. pulmnar recorded in the first part of this paper. 
Without waiting for my final account of the sexual phases of 
the Myzostomes, Beard ('94) has assailed my position with great 
confidence — reiterating his unshaken faith in the »complemental 
male« hypothesis which he advanced a decade ago. He adds a 
few observations made since his dissertation was published. 
In Order that this ghost of a » complemental male« which has 
disturbed the whole subject of the sexual conditions in the Myzo- 
stomes, may at last be definitely laid, I would add to the obser- 
vatioDS contained in the first part of this paper the following con- 
siderations v/hich, I believe, will do away with all the objections 
so studiously brought forward against my views. 
1) Beard’s observations on the sexual phases are confined to a 
single species {M. glahrum). He seems not to have taken the trouble to 
