STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 455 
The animal died on March 24th, 1910. Dissection showed 
that the ovaries had been nearly completely extirpated, with 
the exception of a few large ova and a few follicles. No 
regeneration of the ovaries had taken place. The thumb 
throughout the experiment remained unaltered. 
No. 6. — Female frog, ovaries removed and two testes trans- 
planted November 2nd, 1909. It was injected on March 3rd, 
6th, and 10th with the substance of fifteen testes altogether. 
It remained healthy for two months after this, but died on 
May 25th, 1910. Dissection showed that the ovaries were 
completely gone, except two minute fragments which had 
not regenerated. 
Throughout the experiment the thumb remained absolutely 
unchanged. 
These two experiments may be taken as typical, since in 
none of the experiments on female frogs did any treatment 
result in any alteration of the thumbs to the male condition. 
We may now turn to the effects of castration upon male 
frogs. 
The effect of complete castration, both testes being 
removed, differs according to the time of year at which the 
operation is performed. If the frog is castrated during the 
breeding season the pads are very soon shed, and great 
difficulty maybe found in keeping the animals alive. Thus — 
No. 12. — Male frog, weighing 19 grm., with thumb-pads 
fully developed and pigmented, had both testes removed on 
March 5th, 1910. 
On March 24th the external surface of the pads was com- 
pletely shed and the surface was pale and comparatively 
smooth, though unpigtnented papillae of considerable size 
were still present on the pads. 
No. 13. — Male frog, weighing 20 grm., with thumb-pads 
fully developed and pigmented, had both testes removed on 
March 5th, 1910. On March 25th the external layers of both 
pads were completely shed, and the surface was pale, and 
only showed comparatively small papillae. The animal died 
on April 7th. 
