The Sexual Phases of Myzostoma. 
27Ö 
iog the origin in the ovary and the function of the Nährzellen cannot 
be profitably undertaken at the present time. 
3. Neph ridia. Eecent students of the Mjzostomes have de- 
scribed a pair of somewhat convoluted tubules, each beginning with 
an opening into the body-cavity («uteriis«) just back of the ovaries 
and passing ventrally and posteriorly to open into the cloaca. These 
tubules were perhaps seen by Sempee, although in bis Fig. 5 Tab. 4 
they are represented incorrectly so far as their relations to the 
cloaca are concerned. They were also seen and figured by v. Geaff 
('77) in cross-sections, but strangely enough he appears to have re- 
garded them as intestinal diverticula. He denies the existence of 
the tubules which Semper interpreted as the oviducts. The best 
description of the tubules in question is given by Nansen ('85, pag. 78 
PI. 1 Fig. 11 ov)d, Fig. 8, PI. 9 Figs. 10 and 23) who calls them lateral 
oviducts, to distinguish them from the unpaired median oviduct, the 
backward continuation of the »uterus«. Nansen found the epithelium 
of each lateral oviduct to be much ciliated (PI. 1 Fig. 26) and of a 
secretory nature, for »mucous globular secretions of variable size are 
often observed in it, vide PI. 7 Fig. 25a((. These oviducts are also 
shown in Nansen's Fig. 20, 20 a, 21 PI. 9. 
I have had no difficulty in fìnding the j)lateral oviducts« of Nansen 
in the Myzostomes which I have studied, and in tracing the tubules 
from their openings into the body-cavity to their openings into the 
cloaca. Nansen's description is in general correct, but I cannot agree 
with bis Interpretation of these tubules as oviducts. Although he figured 
a number of ova in the tubules in bis diagrammatic Fig. 8 PI. 1, I 
have never yet been able to find a mature and normal ovum in them. 
Sometimes a few immature and obviously decomposing ova may be 
found, but quite as often there are mature spermatozoa, and for this 
reason they might with equal justice be regarded as spermducts. 
When the Myzostom.es are full of ripe eggs, a very little pressure 
will cause them to expell their ova in a pink cloud from Nansen's 
median oviduct, i. e. the opening of the »uterus« dorsal to the cloacal 
orifice, but sections of such pressed specimcns show that none of 
the ova have passed into the tubules through the funnel-like openings, 
as might be reasonably expected if these tubules were really oviducts. 
On the other band the secretory character of the tubules may be 
readily inferred from the small globules which stain very deeply in 
haematoxylin and which are scattered through the cytoplasm of the 
gland-like epithelium of the tubules and through their lumen. This 
Mittheilungen a. d. Zoolog. Station zu Neapel. Bd. 12. 19 
