486 STANLEY C. BALL 



are typical of ripe ova in which maturation has not yet begun. 

 Owing to a relief of pressure both eggs are more nearly spherical 

 than those in the ovary. 



The yolk cells are arranged about these eggs in a loose envelope 

 on all sides except that toward the ovary. Between the yolk 

 cells and the eggs numerous spermatozoa appear. The latter 

 can be traced throughout the length of the antrum and into 

 the atrium where they form a compact mass. 



This specimen leaves no doubt that two normal ova have 

 been freed into a temporary cavity formed at the thin-walled 

 distal end of the oviduct and partly bounded by the ovary, 

 vitellarium and mesenchyme, and are being surrounded with 

 a number of vitelline cells, between which numerous spermato- 

 zoa were actively moving at the moment of fixation. No proof 

 is at hand that one of the eggs came from the right ovary and 

 the other from the left, nor that both came from the right; 

 either case is possible. Their presence near the end of one ovary 

 may signify that both ova were derived from the latter. On 

 the other hand, the possibility is not excluded that one egg came 

 from the other ovary, and by pressure of the tissues was quickly 

 shifted to its present position. In favor of this view it is to 

 be observed in this series of sections that, while the right hand 

 ovum is still in contact with the outer corner of the last egg 

 in the ovary, its mate is entirely free, and has assumed a more 

 nearly spherical shape — two characteristics which an egg would 

 probably possess had it come from the other side of the body. 



That one ovary may contribute two ova to the formation of 

 some capsules, is clear when it is known that occasionally three 

 embryos are found in a capsule. As stated in the introduction, 

 two is the nornaal number, but Linton ('10) and Patterson ('12) 

 both observed capsules with one and three embryos. My ma- 

 terial shows further examples of both; and in addition one cap- 

 sule containing four. Thus it is possible that the two eggs 

 deposited in any capsule may have had a common source, or 

 may have come from opposite sides of the body. The weight 

 of the evidence favors the latter as being of most coimiion occur- 

 rence in Paravortex gemellipara. 



