44 
SPERMATOGENESIS OF NORMAL 
malities in the testes. The spermatozoa were of the varicose 
type, and the divisions of the spermatocytes were characterized 
by multipolar spindles. Whether or not the bird was a hybrid 
could not be determined, but the case is an interesting one from 
whatver standpoint it is considered. Were it not a hybrid 
form, then there are other causes which produce effects in the 
germ cells resembling in appearance those of hybridism. 
This suggests the possibility of producing artificially irreg¬ 
ularities in the division of the germinal cells. If such could be 
accomplished, it would be of great importance in determining 
whether or not variability can be induced in the offspring by 
means of chemical stimulus as well as through hybridization. 
VII. Age, 16 months. Parentage: male, common turtle 
dove; female, Japanese turtle dove. This was the sterile female 
already mentioned. The ovary was very rudimentary. The 
oviduct was of small diameter and but little convoluted. It 
opened normally into the cloaca. The ovary was no longer 
than that of a very young bird, measuring only about 1 mm. in 
thickness and 4 mm. in length. It existed as a horseshoe¬ 
shaped band which bent around the underlying mass of connec¬ 
tive tissue, ganglia and blood vessels. Occasional small ova 
with rudimentary follicles of two or three cells were present. 
In only one instance was an egg found which showed much 
increase in size over the surrounding cells. It had attained to 
a diameter of 75 micra with a nucleus 37 micra in diameter. 
The ovum appeared much as a normal egg of the same size 
would except for the incomplete follicle. 
CONCLUSIONS FROM THE STUDY OF HYBRIDS. 
It appears that in crosses of very divergent species the de¬ 
generative processes in the germ cells are, at a maximum. In 
closely related forms like the brown and the white ring doves 
fertility is not diminished and the. testes seem to be normal 
except for occasional irregularities in mitoses. 
The formation of multipolar spindles in division and the 
unequal distribution of chromosomes seen in many instances 
are among the most interesting phenomena presented. Such 
irregularities, however, occur to a slight extent in normal birds. 
A very careful study reveals the fact that they are more pre- 
