464 
Bulletin No. 162 . — 1915 . 
Since July, 1910, the birds have been more constantly under the 
observation and care of the senior author, but acknowledgment should 
be made to Mr. J. C. Curtis and Mr. F. J. Kelley who have at different 
times assumed a large part of the responsibility for the daily records. 
Upon the senior author also has devolved the entire writing of the 
present report. 
The subjects here brought together are somewhat disconnected, 
but for various reasons it seems best to present such data as are 
available upon them at the present time. The sex ratio in pigeons, 
and the relation of sex to the order of laying of the eggs are of especial 
interest because of the prevailing popular notions on the matter, and 
the fact that these ideas, if true, would be very difficult to explain 
on the basis of our present knowledge of sex determination and the 
physiology of egg production in general. As for the time of laying 
and the time of hatching of the eggs, no statistics we believe have 
ever been published on these points, though general statements 
are common in the literature. Our knowledge of the maturation 
process and the earliest stages of avian embryology are, moreover, 
based very largely on studies made on the egg of the pigeon, and all 
accurate information which can be obtained on processes of egg pro¬ 
duction may be of service in this connection. A knowledge of the 
most probable time of laying of the second egg may especially be of 
use in obtaining desired maturation stages. Finally, although 
the results of the present investigation are largely destructive of the 
popular notions of sex determination and sex control in pigeons, it 
is always an advantage for the practical breeder to know the facts, 
since a knowledge of them may save him much time and effort along 
fruitless lines. 
Investigation on certain of the subjects discussed in this paper 
is being continued by the Department of Experimental Breeding at 
the University of Wisconsin, and will subsequently be reported more 
fully. 
