596 
GEOFFREY SMITH. 
not due to the assumption of definite female characters, but a 
“ reversion” to an “ undifferentiated ancestral condition,” or 
to “ an embryonic state.” But if this were so, the male 
should at any rate assume the comparatively undifferentiated 
state which is actually passed through by the young imme- 
diately after the megalopa stage, and which is retained by 
the female until the first brood of eggs is produced, viz. the 
small, flat, plate-like abdomen and the rod-like form of the 
appendages. Now, as a matter of fact this form is never 
assumed by the male as the result of parasitic castration, the 
female chai-acters being acquired, if imperfectly, yet with the 
definite characters only found in adult females which have 
produced a brood of eggs. This fact alone seems to me to 
demolish the above-mentioned argument, but it is even more 
completely answered by the fact, soon to be described, that 
certain of these male specimens may, on recovery from the 
disease, actually produce ova as well as spermatozoa in their 
regenerated gonads, thus proving that they actually have 
developed true female characters and have not merely re- 
turned to an undifferentiated condition of an altogether sup- 
posititious nature. The infected females, as we have already 
stated, do not show in any character any approach towards 
the male secondai’y sexual characters, though dissection 
proves that in all cases the ovary is arrested in development, 
or even completely aborted. The only secondary sexual 
character affected is the condition of the abdominal appen- 
dages, which may be greatly reduced in size (PI. 30, fig. 12). 
There is never any approach to the male either in the chelae, 
or in the shape of the abdomen, or in the development of an 
appendage corresponding to the copulatory style of the 
male. 
We have now to consider the case of the highly modified 
males which have developed the external female characters 
but retain the copulatory styles. We have seen that in all 
these specimens the gonad is reduced to a few shreds of un- 
differentiated germinal epithelium, and in some cases the 
remains of the vasa deferentia. In a very few cases such 
