PHYSIOLOGY OF REPRODUCTION IN DOMESTIC FOWL. 57 



TABLE I. 



SHOWING THE NUMBER OF MULTIPLE- YOLKED EGGS PRODUCED BY PULLETS 



FIVE TO SEVEN MONTHS OLD. 



No. of Eggs with No. of Pullets Percentage of 



More than one Yolk. Observed. Observed Flock. 



152 80.42 



1 26 13.76 



2 8 4.23 



3 3 i-59 



separate envelopes, are sufficiently well regulated at the begin- 

 ning of laying to result in the production of only normal single- 

 yolked eggs. The other 20 per cent, of the birds produce one 

 to three eggs with more than one yolk. Less than 6 per cent, 

 of the flock, however, show more than one such irregularity 

 while only about 1.5 per cent, show three such imperfections 

 of regulation. It is thus clear that even in young birds ovulation 

 and egg formation is in general a well-regulated process. Dis- 

 turbances in the rhythm are, however, most likely to occur 

 among young birds. 



The question naturally arises as to whether it is the immaturity 

 of the bird or the lack of laying experience which is responsible 

 for the unstable regulation of ovulation. If birds w T hich begin 

 to lay younger show a more decided tendency to produce eggs 

 with more than one yolk while those which are more mature 

 produce only normal single-yolked eggs, it might be concluded 

 that immaturity is associated with a lack of precision in the 

 regulation of the time of successive ovulations. 



Data now being collected at this laboratory will probably 

 be sufficient to answer this question. The evidence at present 

 available, although insufficient to settle the question, suggests 

 that immature birds produce more multiple-yolked eggs than 

 mature birds which have not laid when young. The evidence 

 consists of the three following observations. First, only about 

 one-third of the pullets of all sorts, including many crosses not 

 carrying hereditary factors for high winter production, which 

 are kept at the station, begin to lay before November I. The 

 others begin to lay at varying times up to March. A few double- 

 yolked eggs are produced in every month of the year, but by far 

 the greatest number are produced at the end of September and 



