DEVELOPMENT OF PARAVORTEX GEMELLIPARA 483 



the membranes of the eggs and of the vitelHne cells, owing to 

 irregularities in the contour of the ovary. Wherever the sec- 

 tion is not thus perpendicular it is oblique, and hence the mem- 

 brane is inconspicuous. 



The masses of granules which Patterson interprets as streams 

 of yolk entering the ova can be found in eggs which are not in 

 contact with the vitellaria. In my own preparations I have 

 considered these darker lines of granules as portions of the 

 cytoplasm which retained more stain than that the rest of the 

 cell. 



It is evident, then, that Patterson was misled, both in regard 

 to the relation of the contiguous ova in the posterior end of the 

 ovary, and the relation of the ova to the vitellaria. There- 

 fore I cannot agree with him, either that the vitelline material 

 is pumped directly into the ova, nor that the breaking down 

 of a membrane between two ova is part of a process by which 

 two or more nuclei are enclosed in one capsule. No syncytium 

 is found here. I am not content with the qualification which 

 Patterson introduces as follows: 



"However not in all cases do the two contiguous ova lose their 

 intervening membranes, but some become completely sur- 

 rounded by vitelline cells, which through a process of disinte- 

 gration, form the yolk mass of the definitive capsule." The 

 egg membranes are never so lost. It can be shown that in 

 order reasonably to account for the multiplicity of embryos in 

 capsules of Paravortex gemellipara it is unnecessary to resort 

 to such an extraordinary mechanism as a syncytium in the 

 ovary. 



As to the manner in which two embryos come to lie in one 

 capsule two possible hypotheses remain ; first, that polyembryony 

 occurs in P. gemellipara, or second, that two or more ova are 

 Hberated, and, together v/ith yolk cells from the vitellaria, 

 become simultaneously enclosed within one capsular mem- 

 brane. That the first hypothesis is false there is no room for 

 doubt. Capsules have often been observed in which both ova 

 are undergoing maturation, a state which precludes the possi- 

 bility that a single fertilized egg was enclosed in a capsule and 



JOURNAL OF MORPHOLOGT, VOL. 27, NO. 2 



