CIIAHACTKUS I ONcKHXI'D IX FKClXDri^' 201 



tlircc nu)ntlis of tlic i>ulk't liiyiiiu- \c;\v mark lier irrcalcst susfrptiliility to 

 id\crse en\ ironnioiital infiuoiu'os, it is oiitin-ly probable tliat early inatiirily 

 may enable tlie bird to persist late, as pointed out in seition i. 



Hy ap)ilyiiiji' tlie iiietbod of partial correlation, winler pause duration, in- 

 tensity, degree of broodiness and persisteney are made eonstant and tlie net 

 eorrelation between age at tirst egg and annual egg i)roduetion arrived at. 

 The net eorrelation between age at first egg and annual production is — .0238 

 :t.0177. This insignificant t'onstant clearly discloses that age in itself is not 

 associated with annual ]n"oductioii. Sections 2 ;uid !• make clear the fact 

 that early maturing pullets may carry slightly greater intensity and that they 

 beyond (piestion tend to exhibit greater persistency than late maturing pullets. 

 Thus the high yearly producer must be early maturing not because early 

 maturity itself is of importance but because early maturity has some linkage 

 with high intensity and very intimate linkage with persistency. 



/,'. Letififh of ]V inter Pans-/' anil ^Inumd Pniduction. 



The probabilities are that the domestic hen possesses functional capacity 

 to lay a rather definite number of eggs previous to the time when she must 

 cease laying and renew her reserve of materials necessary in the ctunplex 

 phj'siological processes of egg production. The mean length of the winter 

 cycle for the flocks studied is 52.26 days (Hays and Sanborn, 1926b) and the 

 mean length of winter pause is 32.26 daj's. The standard deviation in winter 

 cycle is ±34.23 days, showing great variability in the length of time the birds 

 may lay before the onset of winter pause. "With these facts in mind, the 

 negative correlation between age at first egg and length of pause observed in 

 section 1 may be understood. Furthermore, there exists an appreciable 

 negative correlation between early hatching and duration of pause as might 

 be anticipated. The tendency to pause in itself is governed by a dominant 

 inherited factor (Hays, 192 1-). 



The net correlation of length of winter pause with annual egg record is im- 

 portant and is determined by making age at first egg, clutch size, total days 

 broody and annual persistency constant. This constant Is — .5487±.0128. 

 Here is shown a rather intimate negative association between length of winter 

 pause and annual egg yield. In the breeding program hereditary pause should 

 be eliminated by the constant use of tested breeding males and females, and 

 environmental pause should be controlled by time of hatching and methods 

 of management. 



/->. Average Size of Winter Clutch (ind Annmd Production. 



The mean size of winter clutch has already been shown to be specific and a 

 workable measure of intensity. In order to discover the association between 

 mean clutch size and annual production the method of partial correlation is 

 applied. In this instance age at first egg, length of pause, days broody and 

 annual persistency are made constant. The net correlation between winter 

 clutch size and annual production is -f-.t94 lit .0101. This constant is of sulR- 

 cient magnitude to demonstrate that intensity as measured by winter clutch size 

 is a significant characteristic in relation to annual production and of aliout the 

 same importance as duration of winter pause. 



