No. 614] 



EGG PRODUCTION 



73 



of the others. Early sexual maturity is assumed to be a 

 constitutional tendency to begin laying as soon as a suffi- 

 cient body size or body maturity is reached, while late 

 sexual maturity is assumed to be a tendency to delay pro- 

 duction until after body maturity is attained. This head- 

 ing, however, does not refer to the objective attainment of 

 sexual maturity which is shown by the column on "time 

 of first egg." The length of the growth period also is 

 assumed to be determined by the attainment of bodily 

 maturity. 



TABLE I 



Various Combinations of Hypothetical Growth Factors with their 

 Effect on Winter Egg Production 



It appears from this table that early sexual maturity 

 can become fully effective only when combined with rapid 

 growth during a short growth period. 



The effect of the activities of some of these factors as 

 bearing on winter egg production may be given more 

 specifically as follows : If we measure egg production by 

 the number of eggs laid before the 1st of March, assum- 

 ing for the moment that this point represents, approxi- 

 mately at least, a definite point in the history of the egg 

 production of each individual, it follows that the birds 

 hatched during April and May, or to take a definite point 

 for the purposes of illustration— April 15— which mature 

 at five months, as is sometimes the case, will begin to lay 

 September 15 and will lay a large number of eggs before 

 March 1, provided, of course, that they do not moult. On 

 the other hand, true mediocre productivity (slow rate) 

 associated with early maturity will tend to force a bird 



