CHANGES IN EGG PRODUCTION. 115 



Tabic I and Fig. 3.) Although there is a fascinating problem involved 

 in attempting further selection for earlier maturity, such an endeavor is 

 not consonant with the main project. 



Changes in Length of the Initial Cycle and its Complement, the Winter 



Pause. 

 In the station strain of Rhode Island Reds, many individuals produce 

 an initial series of eggs which is followed by a rest period, the winter 

 pause. The trait does not lend itself to ordinary statistical treatment 

 because of its nature, which depends partly on an inherent condition of 

 the strain, and partly on environmental conditions, particularly those 



^^ ■ A 1913-14- 



/\ I9I5-"I6 



//\\ I9I8-'I9 



25 • / / V + '920-^21 



/ r /\ 

 I \ H \ 



10 



5 



10-5 505 90-5 I3a5 I70S" 2105 250 5 



E G & S 



Fig. 11. — Frequency Polygons showing the Percentages of Flocks laying the Given 



Number of Eggs per Year. 

 The curve for 1913-14 is that of the 59 birds kept through the year. (See Table II.) 



that determine the time of year when the birds begin to laj'. Further, 

 it is possible that more than one cycle is involved. The present discussion, 

 therefore, is limited to a general descriptive treatment of the subject, 

 based on experiences with flocks subsequent to those studied in an earlier 

 paper (Goodale, 1918). 



It is now clear that the earlier a pullet begins to lay in the autumn, the 

 more likely she is to exhibit the winter pause. A few early layers, however, 

 go through the entire winter mthout pausing. Roughly speaking, 90 per 

 cent of pullets lajang their first egg early in the season (September) ex- 



