DEVELOPMENT OF PARA VORTEX GEMELLIPARA 487 



In figure 9 are shown several masses of a homogeneous sub- 

 stance which is altogether unlike anything observed in other 

 preparations. This latter fact, together with the arrangement 

 of the masses — more apparent in other sections of the same 

 capsule — in a half circle about the yolk cells which surround 

 the two ova, suggests that the substance is the fluid secretion 

 from the shell glands in the process of being laid down in the 

 formation of the capsular wall. A similar condition was ob- 

 served by Hallez ('09) for Paravortex cardii. 



As the above quotation from his paper points out, Hallez 

 asserts that there is no uterus in Paravortex cardii nor a cavity 

 of any sort at the point of junction between vitellarium, ovary 

 and oviduct. Still he figures a direct continuation of the lumen 

 of the oviduct into the cavity which is receiving a mass of yolk 

 cells. It is true that P. gemellipara possesses no permanent, 

 distinctly limited uterus by whose contractions the yolk cells 

 and ova are molded into a spherical mass to which by accretion 

 the capsular fluid is applied. Nevertheless it is apparent that 

 in P. cardii and P. gemellipara the process is essentially the 

 same as in oviparous worms, differing only because the encapsula- 

 tion cavity is bounded partly by the ruptured and distended 

 end of the antrum femininum and partly by the vitellaria, 

 mesenchyme and ovary. The cavity is indefinite and probably 

 never exactly the same for successive capsules, but there is, in 

 spite of the delicateness of the tissues, sufficient resistance to round 

 off the capsular contents and allow of the laying down of the 

 shell. Thus the process is essentially in agreement with that 

 found by other investigators in related species. 



b. Description of the newly formed capsule. The appearance 

 of a capsule which has just passed from the reproductive organs 

 into the body parenchyma is clearly shown in figures 10 and 11. 

 It lay close outside the uterus, slightly posterior and ventral 

 to the point at which the ovary turned inward to join the 

 vitellaria. It should first be made clear that, whereas living 

 capsules due to their turgidity are smooth in outfine, preserved 

 material shows capsules somewhat shrunken and crowded out of 

 shape by neighboring tissues. 



