RELATIONSHIP BETWEEN LARVAL AND EMAGINAL LEGS OF LEPIDOPTERA. 179 
outlined but not fully grown, just as the larval leg is at its first 
appearance when reproduced after amputation. There is another 
alternative, and that is that the imaginal leg may be wanting beyond 
the trochanter. My experiments are too few to determine which 
distinguishes these cases. 
If the parts are entirely wanting in the imago, it is clear that the 
larval parts that correspond to the imaginal part, whether as partially 
formed or merely germinal material, must have been removed. And, 
further, that the mere basal germinal material that gives rise to the 
regeneration of the limb, has either been removed, or, more likely, has 
not been afforded its proper stimulus. In the other case, if the 
imaginal limb is present, but of reduced size, it is clear that the 
proper larval source of the imaginal limb has been removed, and that 
it has been re-supplied by regeneration. 
If certain portions are of full size, either the larval parts to which 
they correspond have not been removed, or they have been removed 
so early in larval life that regeneration has had time to become 
complete. 
It may be said that if regeneration can re-form the whole limb from 
germinal material at the base of the limb, then it is obvious that 
Gonin’s hypothesis of germinal material existing there is admitted. 
But this is not so. Gonin’s hypothesis is that the germinal material 
for the leg exists there, and that it is employed to form the imaginal 
limb in ordinary. Whereas the true hypothesis is that this regenera- 
tion plasm is not used in any way, and does not develop into anything, 
unless required for its proper function of supplying an amputated 
limb. This becomes evident if we consider the case of a lobster or a 
cockroach, where regeneration takes place when a limb is lost, but 
where there can be no doubt the limb is not grown from the base de 
novo at each moult, in ordinary circumstances. 
I think we may reasonably conclude from the facts observed : 
(1) That the old idea, that the larval leg is the imaginal leg, is sub- 
stantially correct, and that the result of the comparison with trichop- 
terous and other larve, showing that the parts present in lepidopterous 
larve are the femur, tibia, and tarsus, is supported by them. (2) That 
there is germinal material at the base of the larval leg, which would 
under ordinary circumstances be functionless, but on the loss of the 
lee by accident or injury, comes into action and reproduces the lost 
limb, Jarval or imaginal, as the case may be, but the reproduced limb 
is a diminutive sketch of the lost limb, and can only reach a size to be 
functional after further moults. (8) That the progress made in the 
regeneration of the lost part is disclosed at each moult, remaining as 
it were suspended in the intervals; but there is little doubt that its 
real progress takes place during these apparently quiescent intervals. 
It will, 1 think, be safe to conclude that M. Gonin’s hypothesis is 
quite erroneous. 
EXPLANATION OF PratE VI. 
The Plate represents the third pai of legs of certain imagines of 
Porthetria dispar, accompanied by the same legs of the larval skin cast 
at the pupal moult, the left leg having been removed during the last 
larval or some preceding instar. In fig. 3 the right larval leg has also 
been removed. J urther details in text. 
