Feb. IS. i9's Simultaneous Ovulation and Double- Yolked Eggs 379 



POSSIBILITY OF A RELATION BETWEEN THE RATE OF FECUNDITY 

 AND THE TYPE OF DOUBLING OF THE DOUBLE- YOLKED EGG 



It has been shown in previous paragraphs, first, that one-sixth of all 

 the double-yolked eggs show by their structure that the two yolks have 

 passed practically the entire length of the oviduct together (16 per cent 

 have the complete set of egg envelopes common to the two yolks); and, 

 second, that in more than one-third (36.44 per cent) of the cases of 

 double-yolked eggs the two yolks must have been ovulated at an abnor- 

 mally short interval, since these double-yolked eggs were laid on days 

 following the production of a normal egg. Or, to put the matter in 

 another way, in 43 out of 1 18 cases the two yolks must have been ovu- 

 lated in less than the normal time, while in only 19 cases did the two 

 yolks pass the entire length of the oviduct together. The anal5'sis may 

 be carried still farther: Of the 43 cases in which an egg had been laid 

 on the preceding day only 7, or 16.28 per cent, were eggs with the two 

 yolks inclosed in common chalazal membranes — that is, even where we 

 have evidence from the egg record of the fowl that the ovulations must 

 have been unusually rapid the structure of the egg indicates that they 

 were simultaneous in only a small percentage of the cases. This is 

 shown in the first column of Table II. This column also shows that in 

 a few of these cases the entire thick albumen envelopes of the two yolks 

 are separate. This indicates that the two eggs have not united until 

 very near the end of the albumen-secreting portion of the oviduct. 



Table II. — Number and percentage of each type of double-yolked eggs occurring as single 

 eggs, or preceded or followed within one day by a normal egg 



