108 MASS. EXPERIMENT STATION BULLETIN 211. 



Successive years do not represent successive generations. The later 

 years include the offspring of selected parents belonging to several 

 generations. 



Floor eggs are excluded from all the data used in this paper. Arti- 

 ficial lighting has not been used. 



Because of the prevalence of disease, the whole plant, both college 

 and experimental, was given a thorough cleaning during the summer of 

 1920. All adult birds were disposed of June 1, so there are no annual 

 records for that year. 



Seasons at which Increased Production is most Desirable. 

 The average well-cared-for flock of pullets of American breeds begins 

 production some time in late fall or early winter, reaches its maximum 



15 



15 \\ \ / \^-7 : 



o 



\ 

 \ 





1915-16 



1918-19 



+ 1920-21 







APR. MAY JUN. JUL. AUG SEP OCT NOV DEC JAN. FE5. MAR. 



Fia. 4. — Seasonal Distribution of Production. 

 The right-hand part of the curve beginning with November precedes, chronologically, 

 the left-hand portion. This arrangement emphasizes lack of production in certain 

 months. 



in March or April, and then declines more or less rapidly toward zero the 

 following autumn, as represented in Fig. 4. The curve starts at the high 

 point in April and ends at the high point in the preceding March, instead 

 of starting with the beginning of production, as is customary. This ar- 

 rangement emphasizes the hollow between the two high points. It is 

 clear that if good production can be obtained in October, November and. 



