118 MASS. EXPERIMENT STATION BULLETIN 211. 



1918-19.) The highlinc flock of 1916-17 averaged 105 eggs during the six 

 non-broody months, November to April, while for the six broody months 

 following, May to October, the average was only 70 eggs. Leghorns, on 

 the other hand, continue production at a relatively high level all summer, 

 and first decline sharply in early fall. Kirkpatrick and Card (1917) give 

 data showing a parallelism between degrees of non-broodiness and summer 

 production. The several races, viz., Rocks, Wj^andottes, Reds and Leg- 

 horns, lay nearly the same number of eggs per bird in ]\Iarch and April and 

 do not differ much in production prior to this date. But during May, June, 

 July, August and September the Leghorns, having the smallest amount 

 of broodiness, lay much more heavily than the other breeds, while the 

 Reds, the most broody race, give the poorest summer production. The 

 Rocks and Wyandottes, which are ver}^ much alike in amount of broodi- 

 ness and intermediate between the Leghorns and Reds, are much alike 

 in their summer production which is intermediate between that of the 

 Reds and Leghorns. 



A striking illustration of the loss due to broodiness in an individual 

 bird is shown by B8316, whose egg record is given in Fig. 16. If she had 

 not become broody, but had instead continued to lay through June, July 

 and August at the rate of 26.4 eggs (her average for the seven months 

 preceding), her annual production would have been 306 eggs, 27 more 

 than her actual record of 279 eggs. (The pause in September looks much 

 like a broody period, but she did not stick to the nest, and therefore was 

 not put in the broody coop.) 



The first experiment in breeding out broodiness was successful, but at 

 the expense of egg production (Goodale, 1920). The experiment in breed- 

 ing broodiness out of the high hne and still maintaining production is 

 not 3'et complete, but gives promise of success. 



Changes in Date of Last Egg. 



The dales of last egg and of first egg determine the length of the an- 

 nual period. The two limiting dates are treated separately, because it 

 seems probable that date of last egg results from the action of some inter- 

 nal mechanism the nature of which is unknown. ^AQiile practically all 

 birds are laying from the middle of March to the middle of June, after 

 this, one by one, the birds stop lajing, not to resume until next season. 

 The majority, however, continue production till the middle of September, 

 the mean date of last egg being near October 1 in 1914 and 1919. Cessa- 

 tion of production has a genetic foundation, as is indicated by the behavior 

 of various families in this respect, som.e stopping earl}^ and others late. 

 Moreover, many of the best layers show a tendency to continue production 

 indefinitely. 



The lack of evidence that the average date of cessation of production 

 has been advanced well into the fall maj^ be associated with lack of especial 

 effort to secure by breeding continued production late into the fall, — 

 an effort that did not seem worth while till after broodiness had been 

 bred out. 



