On Dissotrema papillatum. \\ 



spaces left by the enclosed organs above mentioned are filled by 

 a loose parenchyma, in which a few gigantic cells, probably myo- 

 blasts, with well stained cytoplasm and large processes directed 

 towards the inner muscular coat of the penis are present. The 

 outer muscular coat of the penis sac appears to be the product of 

 about five myoblasts much smaller than the principal ones of the 

 pharynx, which are closely applied to the outer surface of the sac 

 and send out a sarcoplasmic mantle surrounding it. They are in- 

 constant in position but are mostly situated on the dorsal side of 

 the sac. 



The ovary is a rather small, subglobular organ situated 

 on the right side of the median line, roughly between the 

 middle and the last third of the body length, near the dorsal 

 side (figs. 1,3, 4). It is surrounded by a thin membrane 

 with an opening at the anteromedian corner of the ovary, where 

 the oviduct takes its rise. The membrane is surrounded by 

 a layer of very fine circular muscle fibres, and near its opening 

 there are two nuclei embedded in it, probably the nuclei of the 

 matrix cells. The contents of the ovary consist entirely of ova in 

 different stages of development, the smaller and immature ones 

 lying close together at the blind end of the ovary, and the larger 

 and maturer ones near the oviduct. The latter begins at the 

 opening of the ovarial membrane above mentioned and is imme- 

 diately expanded into a small chamber, in which spermatozoa are 

 usually present, and which may therefore be called the insemina- 

 tion chamber." From this the oviduct continues its course trans- 

 versely across the median line towards the left side, and after 

 receiving the openings of the seminal receptacle, the Laurer's 

 canal and the median yolk duct on its way, expands into the 

 ootype, which is an ellipsoidal organ situated in the left half of 

 the body close to the median line and surrounded by the nume- 

 rous glands of Mehlis, or shell glands (fig. 4). The ootype is con- 

 tinued into the uterus which makes a few windings in the left half 

 of the body, between the penis sac and the seminal vesicle. At 



* Looss calls it " Befruchtungsraum " in several of the distornes described by him in his 

 publication of 1894. 



