BULLETIN 228. 
FACTORS INFLUENCING THE SIZE, SHAPE AND 
PHYSICAL CONSTITUTION OF THE EGG 
OF THE DOMESTIC FOWL* 
: : V; ; > ■ 
* O 3 ^ J 3 » > O 9 * 
1 ° . ’ % * ' * 
Maynie: R. Curtis. 
3 -> 3 3 
In a study 'pt the physiology of reproduction in the domestic 
fowl one miist soon recognize the fact that the number of eggs 
produced is only a rough measure of the reproductive activity 
for the eggs produced are not all equivalent. The complicated 
physiological processes involved in the production of an egg 
are so influenced by both heredity and environment that. they 
result in quite unequal products. Eggs differ greatly in every 
character. The scientific and economic importance of differ- 
ences in size and quality is obvious. 
Investigations on inheritance in poultry have been in progress 
at this laboratory for several years. In this work tue eggs oi 
about two hundred hens of one breed are handled individually 
each season. The variation in these eggs is very great. The 
four following facts in regard to it are apparent. 
i. The eggs of different individuals of the same strain vary 
in size, shape, color and markings. 
* This paper is an abstract, setting forth the more important results 
and conclusions, of an extended paper by the same author, published 
under the following title: “A Biometrical Study of Egg Production in 
the Domestic Fpwl. IV. Factors Influencing the Size, Shape and 
Physical Constitution of Eggs,” in Archiv fuer Entwicklungsmechanik 
der Organism (Roux). Bd 39, pp. 217, 1914. The three previous 
papers in the series are : 
Pearl, R. and ^Surface, F. M. A Biometrical Study of Egg Produc- 
tion in the Domestic Fowl. I. Variation in Annual Egg Production, 
U. S. Department of Agr., Bur. of Animal Industry, Bui. no, pp. 1-80, 
1909. II. Seasonal Distribution of Egg Production. Ibid. pp. 81-170, 
1911. III. Variation and Correlation in the Physical Characters of 
the Egg. Ibid. pp. 171 — , 1914- 
8902b 
