SEX STUDIES. XI ae 
indications of recent or present activity in both the male and 
female parts of the gonad. 
The study of the external characters and behavior of these 
hermaphrodite birds shows a great variety of combinations. Evi- 
dently the body shape and carriage and the plumage hang to- 
gether more consistently as secondary sex characters than the 
spurs, comb and: wattles. The latter group vary too much to be 
considered as proofs of maleness or femaleness. Sex behavior 
varies all the way from complete indifference to active reproduc- 
tion. Three of the birds show double sex behavior acting as a 
male or female under different conditions at the same general 
period, or showing a gradual change from the behavior of one sex 
to that of the other. A case somewhat similar to that of 1616 
has been described by O. N. Eastman in the Poultry Advocate 
for September, 1916. At first he did not know whether to class 
this bird as a pullet or a cockerel, but as she became more mature 
she looked like a pullet with a head like a cockerel. She began 
to lay in November, 1915, while housed in a pen with pullets 
and one cockerel. This one cockerel chased her so incessantly, 
as one male bird does another, that she had to be removed to a 
pen with only pullets. In August, 1916, she was seen to chase 
and mate with a pullet, and she repeated this behavior several 
times. This comparison will be taken up again after the full 
description of the anatomy and histology of the sex organs of 
these birds. 
The two guinea chicken hybrids were entirely male in external 
characters, but absolutely indifferent as to behavior. They stood 
around the pens in much the same way as the Holland birds, 
taking no interest in either males or females. We shall see later 
this indifferent behavior is not accompanied by any gross ab- 
normalities in the form of the reproductive organs—that is, not 
to such anomalies as an oviduct or oocytes, but to a lack of dif- 
ferentiation in the testis tissue. 
