JOURNAL OF ACRKLlTim RESEARCH 
VOL. XXVIII Washington, D. C., April 19, 1924 No. 3 
THE RELATION OF ANTECEDENT EGG PRODUCTION TO 
THE SEX RATIO OF THE DOMESTIC FOWL 1 
By M. A. Jull 
Senior Poultryman, Bureau of Animal Industry , United States Department 
of Agriculture 
INTRODUCTION 
In the domestic fowl comparatively little work has been done to determine 
the normal sex ratio and still less has been done to determine what factors might 
operate toward a possible modification of the normal sex ratio. As a contribu¬ 
tion in this direction an experimental study was undertaken to determine the 
sex ratio in the domestic fowl from the time of commencing to lay to practically 
the end of the first year of production. Under the direction of Dr. L. J. Cole, 
of the department of genetics of the University of Wisconsin, the plan of the 
work was originally outlined in 1919 and was continued for three consecutive 
years. Among other things the plan of work involved a study of the following 
topics: 
1. The normal sex ratio. 
2. The relation of prenatal mortality to the sex ratio. 
3. The relation of egg production to the sex ratio. 
4. The relation of egg weight to the sex ratio. 
5. The relation of yolk weight to the sex ratio. 
6. The relation of egg water content to the sex ratio. 
In this paper it should be understood that the term “sex determination” has 
reference to the causes which lead to the production of an individual of one or 
the other sex. During recent years considerable progress has been made in 
arriving at a more complete understanding of the causes which determine sex 
but this does not necessarily imply an increased ability to control sex. The 
term “sex control” is understood to imply that the causes which determine sex 
are more or less amenable to human control. 
There are many investigators who believe that the presence or absence of a 
second sex chromosome constitutes one link only in a series of events that precede 
the development of sex. The opinions of these investigators range from those 
in which the sex chromosomes are regarded as playing an insignificant r61e in sex 
determination to those in which the internal mechanism is regarded as being 
really responsible for the control «of ‘sex but where external conditions may be 
operative to a minor extent in modifying sex development. The question 
naturally arises as to whether sex determination involves an irreversible tendency 
to the corresponding sex differentiation, or whether such differentiation may 
be controlled or even reversed. 
1 Received for publication April 26, 1924. The experimental part of the work was conducted in the 
department of genetics, Agricultural Experiment Station, University of Wisconsin, and at Macdonald 
College, St. Anne d’Bellevue, P. Q., Canada. The study was completed in the U. S. Department of 
Agriculture. Published with the approval of the director of the Wisconsin station as Paper No. 46. 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXVIII, No. 3 
Apr. 19,1924 
Key No. A-77 
