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Abnormalities of Reproductive System found in Frogs. 251 
seminal tubules upon the surface of the testis. If this peritoneal coat of 
the testis is stripped off, all the pigment can be removed with it (Fig. 22). 
In the case of the gonad of frog No. VIL, as in all others, the abnormal 
pigment upon the outer border of the testis (or amid the spermatic tissues) 
consisted of polygonal masses of pigment exactly similar to those of the 
animal pole of the normal ovum (Fig. 23). This pigment is not found upon 
the peritoneal coat of the gonad but within it, and it is ovarian and not 
spermatic in origin. The presence of this alone is sufficient to indicate 
that other ovarian tissues are, or have been, present in the gonad. The 
increase in pigmentation is relative, and is due to the fact that when the 
ovarian tissues are undergoing degeneration and consequent absorption, or 
extrusion, the pigment, being one of the most resistant of the ovarian tissues, 
remains after the other more delicate tissues have disappeared. There is no 
reason to assume that degeneration is associated with an actual increase in 
the amount of pigment therefore, and if the pigment present in certain 
gonads of these cases were spread over an ovary of ordinary size, the colour 
of the gonad would not be remarkable. 
Overgrowth of the connective tissue, on the other hand, is an actual 
feature of degeneration, and this was more or less pronounced in every case. 
There was no correlation between the amount of spermatic tissue present in 
the gonads and the degree of degeneration in the ovarian. Quite a small 
amount in Cases Nos. I. and II. was associated with appreciable degeneration 
in the ovarian tissues of both gonads. In these cases also it is to be noted 
that not only was the ovarian tissue of the gonad in which spermatic tissue 
was also present undergoing degenerative changes, but also that the ovary 
of the opposite side was similarly affected, though to a less extent. 
The graded conditions found in these cases demonstrated that exception- 
ally both ovarian and spermatic tissues can become expressed in one and 
the same gonad of the frog, and suggest that the expression of the spermatic 
may not occur until the ovarian have attained functional maturity. Also 
it is seen that if the expression of the spermatic tissues is responsible for 
the coincident degeneration of the ovarian tissues, then the agent must be 
blood-borne as those of the gonad of the opposite side are equally affected. 
Such action could be explained in terms of the hormone theory, assuming, 
contrary to the conclusions of Lillie concerning the free-martin,! that there 
is a conflict of hormones in the case of the frog, that of the testis being far 
more powerful than that of the ovary. 
The cases are so arranged as to suggest that the conditions found in the 
1 Journal of Kxpervmental Zoology, vol. xxiii. p. 371. 
VOL. XX. Z 
