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THE AMEBIC AN NATURALIST [Vol. LII 



urally occurs and it also represents an extension of the breeding season. 



The fourth period (September and October) is not easily separated 

 from the third in respect to laying, but in general it is the period of 

 moulting. ... It is characterized by reduced laying and marked in- 

 creased variability. 



It is not clear from their accounts whether or not they 

 consider that these periods extend through the second 

 year or whether they are to be considered as characteris- 

 tic solely of the pullet year. 



Just how far the data on Barred Plymouth Rocks are 

 applicable to our Rhode Island Reds is somewhat uncer- 

 tain. At the outset it is evident that the small per- 

 centage of birds that show an interruption in their winter 

 laying because of the presence of a broody period afford 

 no evidence either for or against the existence of a winter 

 cycle. Of the birds that do not go broody during the 

 winter two classes can be distinguished, viz., those that 

 show an interruption in their winter laying and those that 

 do not. In the 1913-14 flock and in the 1915-16 flock 

 from the original source, a large percentage of the birds 

 show no interruption in production, not even a slump in 

 the rate of production. Such birds lay at an approxi- 

 mately constant rate through the late fall and winter 

 months, and on through the spring. Among the records 

 of the main portion of the 1915-16 flock are many that 

 show an interruption or else a slackening of production. 

 Of these birds it can be said that they have a winter cycle. 

 But there are two points about these records that make 

 it difficult to interpret the interruption in production as 

 an index of a cycle. First, the interruption may occur 

 at almost any time during the winter followed by a re- 

 sumption of production in mid-winter, and second, some 

 individuals show more than one period of nonproduction. 

 While there is definite evidence that a winter cycle exists 

 in some but not all Rhode Island Reds, the possibility 

 that some at least of these interruptions of production 

 may be due to environmental factors must be fully recog- 

 nized. 



