TADPOLE RAISED BY ARTIFICIAL PARTHENOGENESIS. 215 
fluids were injected into tlie egg, but though very large 
numbers were treated, only one abnormal tadpole was procured. 
The data got from these experiments and from those since 
carried out by myself seem to show that there are almost 
certainly other factors in the problem, as, for instance, in one 
batch of eggs pierced by a solid needle a very good percentage 
of tadpoles was got, while in another lot pierced by a hollow 
needle, not one ev.en segmented. Nevertheless the whole 
series of experiments clearly showed in my case that the 
hollow needle was the better. Individual frogs differed 
markedly in the number of tadpoles raised from their eggs. 
I pricked five thousand eggs of R. temp or aria and raised 
about fifty tadpoles to the closure of the neural folds. There 
were, as is usual, many abnormal specimens, and the death- 
rate of those which hatched was high. Without going into 
details, it may be mentioned that fifteen tadpoles were raised 
to a stage when the external gills become covered by the 
epidermal overgrowth. Two of these were scarcely able to 
swim, and they soon died. Of the remainder all died except 
two, just before their hind limbs broke through. Those which 
died at this time did so, I believe, because the weather was 
most inclement, for the tadpoles born under natural con- 
ditions in the ponds were extremely backward for the season 
of the year. One of the survivors died at the critical period 
when the germ cells were beginning to become grouped in 
the manner which shows their sex. I believe this one would 
have been a male, but there was still undifferentiated material 
in the gonad. The sole survivor grew at a great pace and 
quickly outstripped the controls, so that it was nearly two 
and a half times normal size. In Text-fig. 1 and 2 are natural 
size drawings of this tadpole and a normal control raised 
n the same way ; the parthenogenetic tadpole is normally 
proportioned, its hind limbs, tail, faeces, and its general 
outward morphology being proportionately large. The rectum, 
as was shown by the size of its faeces, and as subsequent 
dissection showed, was also very large. 
At the age of three months the tadpole was placed in an 
