484 STANLEY C. BALL 



subsequently divided into two cells, each capsule developing 

 into an embryo. 



There remains the hypothesis that any capsule which con- 

 tains a certain number of embryos originally had deposited 

 in it the same number of eggs. A priori it is to be expected that 

 such a process occurs here, for both von Jhering ('80) and von 

 Bohmig ('86) observed in the uteri of the oviparous parasites 

 GraffiUa tethydicola and G. muricicola respectively capsules 

 containing usually two ova; Bohmig states that each ovary 

 contributes one egg. The same mechanism is probably in- 

 volved in the formation of the capsules of the oviparous speci- 

 mens mentioned above and in the viviparous Paravortex gemil- 

 hpara. In the former two species the capsules pass out of the 

 animal through the atrium and genital pore, while in the case 

 of P. gemellipara they never enter the atrium, but break out 

 of the antrum into the mesenchyme. 



Finally Hallez ('09) observed the formation of the capsule 

 in Paravortex. To quote: 



Chez Paravortex cardii, comme dans I'espece precedente, il n'existe 

 ni uterus, ni cavite d'aucune sorte au point de jonction du lecithogene, 

 de Tovaire et de I'oviducte. 



Quand le cocon commence a se former, il se produit un afflux de 

 cellules vitelline autour des ovules mtlrs qui ne sont pas encore complete- 

 ment detaches de I'ovaire, afflux qui distend la membrane proprede 

 I'ovaire et refoule le tissue conjonctif lateralment, c'est-a-dire du 

 cote ou la resistance est moindre. II se forme ainsi une hernie qui 

 s'accroit davantage a mesure que le nombre des cellules lecithoferes 

 augmente autour des ovules mArs .... 



On observe a ce moment des spermatozoides dans la partie de I'ovi- 

 ducte voisine de I'ovaire . . . , tandisque I'atrium femelle et 

 une partie de I'oviducte contient un cylindre d'une substance amorphe, 

 transparente, coagulee par les reactifs .... Cette substance, 

 qui ne peut etre que la produit de secretion des glandes coquillieres, 

 adhere par places a la paroi de I'atrium comme si elle etait glutineuse. 



Hallez finds that from two to four ova are thus inclosed in 

 a capsule. Since the ovaries of P. cardii consist at their pos- 

 terior ends of several eggs, there is greater likelihood that more 

 than one at a time will be freed than there is in the case of P. 

 gemellipara. As a matter of fact Hallez finds a larger number 



