No. 615] EGG PRODUCTION 215 



not persistent layers during the fall, while some birds 

 with low winter records are good fall layers. 



Other kinds of cycles, which are described in the fol- 

 lowing paragraphs, have been noted in the Ehode Island 

 Reds. In broody individuals, where the practice is fol- 

 lowed of " breaking up" the hen, a series of cycles is in- 

 troduced, marked by broody periods alternating with an 

 egg production period. If the natural course of events is 

 not interfered with in the case of broody hens, the broody 

 period lasts until the chicks have hatched. Then the 

 period of rearing takes place. Toward the end of this 

 period the hen begins to lay and the cycle is repeated. 



There is also a short time cycle of one or two weeks 

 which needs little discussion at present. It is shown by 

 an acceleration in rate of egg production followed by a 

 decline somewhat as follows: Egg— blank— egg— egg- 

 blank — egg - egg— egg - blank - egg- egg— egg-egg- 

 blank - egg — egg - egg - egg — blank - egg -egg- egg - 

 blank— egg— egg— blank— egg— blank — egg — bla nk — egg 

 —blank— and repeat. Although one often finds records 

 that approximate closely the above scheme, their rarity 

 suggests either that the fluctuations in rate are due di- 

 rectly to some extraneous circumstance or, if there is a 

 fundamental rhythm of this sort, that it is subject to dis- 

 turbance from the environment. Whatever may be the 

 cause, at present it is doubtful if it is indicative of an 

 internal factor. 



The next type of cycle is that exhibited by certain hens 

 which lay at a relatively high rate for a time and then 

 stop. This period may correspond to the term often used 

 by poultrymen when speaking of a hen's clutch. Here 

 again we are confronted by doubt as to the causation 

 of these blanks, for many hens do not have such pauses 

 in production. Once they begin laying they continue 

 without any considerable vacant period (not exceeding 

 three or four days) until the onset of the first broody 

 period. 



Stamina.— A strong bird is readily distinguished from 

 a weak one, but it is difficult to separate the birds per- 



