INTERNAL FACTOES INFLUENCING EGG PRO- 

 DUCTION IN THE RHODE ISLAND RED 

 BREED OF DOMESTIC FOWL II. 



DR. H. D. GOODALE 

 Massachusetts Agricultural Experiment Station, Amherst, Mass. 



Cycles.— By cycles of egg production are understood 

 the existence of periods of egg production alternating 

 with periods either of decreased egg production or entire 

 cessation of egg production. These cycles may be either 

 long or short. The long-term cycles may have a period 

 of a year. Shorter cycles exist with a period of three or 

 four months, i. e., winter, spring and summer and fall. 

 There are still shorter cycles with periods measured in 

 weeks, while one may also recognize irregular cycles. A 

 litter, as defined by Miss Curtis ('14), is a short period 

 of egg production alternating with a non-productive 

 period and is well illustrated by broody birds, though it 

 may occur in non-broody individuals. A "clutch," ac- 

 cording to Miss Curtis, is the set of eggs produced on 

 consecutive days. Its termination is marked by the ap- 

 pearance of a blank day. 



The form of the yearly cycle depends to a consider- 

 able degree upon some of the internal factors under dis- 

 cussion, that is, it varies in different individuals. Egg 

 production, as a rule, begins in the fall and winter, and 

 continues at a fairly constant rate in most individuals 

 until spring, when the rate rises somewhat in many indi- 

 viduals. Those that have been laying at a relatively high 

 rate do not show this acceleration, at least not in as 

 marked a degree. Sooner or later in a broody race 

 broody periods appear, which interrupt egg production at 

 fairly constant intervals. The rate, however, during the 

 nonbroody periods shows no slackening, but on the con- 

 trary a very slight acceleration may be demonstrated, so 

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