THE AMERICAN NATURALIST [Vol. LII 



for May-hatched pullets be examined it will be noticed 

 that there is a large percentage of pullets in the 16-20, 

 21-25, and 26-30 groups. If the average monthly pro- 

 duction of about 10 eggs be added to these groups, most 

 of them become over-thirty birds and the percentage of 

 over-thirty birds becomes nearly the same as that for the 

 April-hatched pullets. This is important, since it indi- 

 cates that May-hatched Rhode Island Eed pullets mature 

 too late to furnish data comparable to Pearl's Barred 

 Plymouth Rocks, for which it is stated (Pearl '15) that 

 April- and May-hatched pullets alone give normal records. 



Birds that begin to lay by January 1 and lay at the 

 rate of 15 eggs per month would lay 30 eggs before 

 March 1. This rate is about the lowest continuous pro- 

 duction that has been noted, for birds that lay at a less 

 rate usually lay intermittently. Pullets that lay at the 

 rate specified and which begin sufficiently early in the 

 season make very good winter records. In a recent 

 paper Pearl, '156, has remarked : 



Any bird laying 18 or more eggs per month in the months of Novem- 

 ber, December, January and February may certainly be regarded as a 

 high winter producer. 



The statement as written might imply that this rate is 

 maintained throughout all four months, but, as this means 

 72 eggs and as the context implies, we take Pearl's state- 

 ment to mean 18 eggs for any one month. At this rate a 

 bird beginning to lay January 1 would lay 36 eggs before 

 March 1. Since, however, the mode of the frequency 

 curve of age at first egg falls at the 251-260 days groijp, 

 and since the median also falls near this group, it means 

 that nearly one half of a flock of pullets hatched May 1 

 will not begin to lay till after January 15, and therefore 

 will lay less than 30 eggs. The slope of the curve indi- 

 cates, moreover, that the upper limit of the range falls at 

 about 311-320 days, which means that a few individuals 

 begin to lay so late in life that they can not be expected 

 to make normal records. Ten months from hatching time 

 brings birds hatched the last of April into laying some 



