290 MAINE AGRICULTURAL EXPERIMENT STATION. I915. 



(5) The most probable interpretation of this phenomenon 

 is that the two components unite at any level of the oviduct 

 from the funnel mouth to the isthmus ring. 



(6) The conclusion that the union of the component eggs 

 occurs indiscriminately at all levels of the oviduct is strongly 

 supported by the fact that the percentage of eggs of each type 

 closely proportional to the percentage of the portion of the duct 

 in which the union of two eggs would give double-yolked eggs 

 of that type. 



(7) In 36.44 per cent of the double-yolked eggs the ovula- 

 tions which furnished the two yolks must have been separated 

 by an abnormally short interval, since a normal eg^ had been 

 laid on the preceding day. 



(8) An examination of the egg structure, however, shows 

 that the two yolks have passed the entire length of the duct 

 together in only 16.28 per cent of the cases in which the ovula- 

 tions are known to have been usually rapid. 



(9) While a heightened rate of fecundity may result in the 

 production of an egg of any of the three types, 68.75 per cent 

 of the eggs of type III are single eggs. It seems probable that 

 many of them have resulted from the delay of the first egg in 

 the oviduct. 



(10) The ovary of each pullet which had just laid a double- 

 yolked egg as her first egg contained two normal separate folli- 

 cles which had separate blood supplies. In these cases, however, 

 the doubling of the egg had occurred near the end of the albu- 

 men-secreting region. 



fii) In a case in which there was evidence from the struc- 

 ture of the egg that the two yolks had passed the entire length of 

 the oviduct together the two follicles were also quite distinct, 

 Vv^ith separate blood supplies. 



(12) This, together with the fact that in only a small per- 

 centage of double-yolked eggs is there any evidence of simul- 

 taneous ovulation, indicates that the fusion of follicles and a 

 resulting common blood supply is by no means the usual cause 

 for the production of a double-yolked egg. 



(13) A simple normal follicle furnished the yolk with two 

 germ disks; hence, the fusion of the oocytes (if this was the 

 origin of the two germ disks) must have occurred before the 

 formation of the follicle. 



