No. 615] 



EGG PRODUCTION 



213 



As already noted, there are many Rhode Island Reds 

 which show no sign of a winter cycle. Whether this 

 means that such birds do not have a winter cycle, or 

 whether it means that some other factor covers up an un- 

 derlying cycle is uncertain. In many instances these 

 birds are very much like the Barred Plymouth Rocks 

 noted by Pearl and Surface, '11, who state : 



Many birds of course have no proper winter cycle at all. They begin 

 to lay for the first time in January or February and keep on laying 

 without any large break straight through the spring cycle. 



But there are many other Rhode Island Reds that begin 

 to lay in October, November and December and lay through 

 the winter and spring without any breaks whatsoever. 

 Moreover, those birds that begin to lay in January or 

 February for the first time very rarely show any break 

 whatsoever. For these instances where the birds begin 

 to lay late in the winter it is conceivable that the winter 

 cycle might extend well into March but that the compara- 

 tively mild weather at that season of the year would tend 

 to eliminate the rest period and thus conceal the winter 

 cycle. But this argument cannot be applied to those in- 

 stances in which the laying is continuous from its start in 

 October, November or December right through the spring. 

 There seems no reason to speak of a winter cycle for this 

 class of Rhode Island Reds. 4 



The spring cycle, in Rhode Island Reds, in so far as it 

 can be differentiated from the winter period, differs 

 chiefly from that of the Barred Rocks in extending nearly 

 through June, since the end of June marks the point at 

 which practically every bird that will go broody has be- 

 come broody at least once. Egg- production is at its maxi- 

 mum at the beginning of this period due to active laying 

 on the part of practically all individuals but falls sharply 



Island Reds as a whole. There is some ■■. - . , v, r. that the winter 



cycle is a Mendelian recessive, the dominant allelomorph being continuous 



