The Sexual Phases of Myzostoma. 
247 
in surface views or in sections. This simplification of stFucture extends 
also to tlie internal sexual organs. All three specimens were in about 
the same phase of reproductive activity. Curiously enough these 
specimens, notwithstanding tbeir enclosure in the thickwalled cysts 
and long sojourn in alcohol, were in a most excellent state of pre- 
servation. 
PI. 11 Fig. 33 represents a cross-section of one of the specimens 
through the middle of the body. The crescentic outline of the section 
is sufficiently explained by a glance at the surface view in Fig. 31. 
The posterior end of the retracted pharynx and the tips of the 
intestinal ramifications [int.r] which run forward into this region of 
the body are cut transversely. The spacious body-cavity in which 
the intestinal ramifications lie, is filled with mature or nearly mature 
vesiculated ova (o). At first I had great difficulty in finding the 
ovaries, because I sought for them where they are found in other 
species, viz. dorsal to the main branches of the intestine and near the 
Center of the body. They were finally found in all three specimens 
as two deeply staining cell-masses beneath the intestine some di- 
stance from the raid-ventral line and very dose to the ventral wall of 
the body [ov). Under a higher magnification (PI. 11 Fig. 34) the pale 
oocytes and deeply staining accessory cells were very easily resolved. 
Near the edge of the mass the typical triplet-cells were seen floating 
in the body-cavity or already applied to the peritoneal epithelium and 
beginning tbeir growth. A study of the consecutive sections shows 
that the ovaries are attached to the bases of a pair of septa at a 
point where these latter merge into the parenchyma of the ventral 
body-wall. In PI. 12 Fig. 38 I reproduce a section passing through 
the insertion of an ovary. It will be seen that it does not ditfer in 
any important particular from the ovary of M. cirri/erum. 
While the ovaries of M. helli have taken up a lateral and ventral 
I Position nearly corresponding to the position of the testes in other 
species, the testes of this peculiar form are found in a position 
which recalls that of the ovaries of other species, viz. dorsal to the 
intestine and its main diverticula and in the middle of the body. 
The whole mass of the testes (ts) where it projects into the body-cavity 
is divided into three lobes by two dorso-ventral septa. The median 
! mass is the largest and projects into that portion of the body- 
cavity which other investigators have called the »uterus«. In the 
j testicular masses the minute cells may be observed in all stages 
I of spermatogenesis. The extremely small mature spermatozoa pass 
