STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 453 
cava. It is quite possible, therefore, that the fertile eggs 
produced by the operated lien were derived from the 
remains of the ovary, which had not been completely 
removed, and not from the ingrafted ovary. The fact that 
the chicks exhibited coloration characters similar to the bird 
from which the ingrafted ovary was obtained may possibly 
have been due to the male or female used in the experiment 
belonging to an impure strain of whites, which normally 
threw chicks with black coloration. Another possibility is 
that the ingrafted ovary contained some nearly ripe follicles 
which actually did come to maturity and gave rise to the 
fertilised eggs, but that the ovary subsequently degenerated . 1 
Setting aside this experiment, the remarkable difference in 
the fate of transplanted gonads according as they are trans- 
ferred to another animal or left in the body of the same 
animal may be considered further in its theoretical bearings. 
In both cases we have found that the mature, fully formed 
spermatozoa undergo destruction. The cause of this destruc- 
tion seems to be connected with the abnormal vascularisation 
of the testis from a source other than the normal one. It 
would seem to indicate either that the ripe spermatozoa in 
the testis are not merely passively stored there, but that they 
require special substances in the nature of food-materials or 
oxygen, which they do not obtain from the abnormal vascular 
supply, or else that the abnormal vascularisation brings in 
blood with properties toxic to the spermatozoa. The latter 
explanation appears more reasonable from the following con- 
siderations. One of us has repeatedly observed in the case of 
the serum of a great number of animals (frogs, birds, and 
mammals) that the normal serum of an animal agglutinates 
and dissolves the spermatozoa derived from the same animal. 
1 Since the above was written, Davenport (' Journal of Morphology,’ 
vol. xxii. No. 1, p. 111. 1911) has repeated Guthrie’s experiments and 
finds that the engrafted ovary always degenerates, thus supporting the 
interpretation given above. We have not dealt here with the question 
of transplantation of gonads in Invertebrates, where the chance of 
success with allo-transplan tat ions appears to be much greater (see the 
important papers of Meisenheimer, and more recently, Kopec [14]). 
