572 



Journal of Agricultural Research 



Vol. XII, No. 9 



Mendelian scheme, "no winter cycle" being the dominant allelomorph, 

 "winter cycle" the recessive. 



Before considering the evidence for this scheme there are certain 

 pecuUarities of the character that should be listed. 



First. The character does not come to visible expression in the male; 

 hence, his gametic composition can be made out only through a con- 

 sideration of his maternal ancestors, his daughters, and his sisters. 



Second. The character is a physiological one, subject to possible in- 

 fluences by the environment, and perhaps to other internal factors con- 

 cerned with &gg production. 



Third. Pauses distinct from those indicative of the winter cycle but 

 likely to be mistaken for them may occur. 



Fourth. Difficulties are encountered in classifying certain individual 

 records, such as records with several very short pauses, a single very 

 short pause, a simple slackening in rate of production without any defi- 

 nite pause, and pauses occurring at the limits of the season. In such 

 instances we have proceeded somewhat arbitrarily. There have been ex- 

 cluded, first, all birds that have laid less than 20 eggs after the first of 

 January; second, all birds showing broody pauses; third, March-hatched 

 birds that begin to lay early in the season, and which molt. 



TablB XI 1 1 . — Progeny of individual pairs of birds of flock of igi6-iy, showing the number 

 with a winter cycle (P), those without (N), and those on which a definite determination 

 could not be m,ade {X) 



