460 Mr Brindley , Regeneration in Samia ailanthus. 
suggested by Newport’s result that there is great want of uni- 
formity in the regeneration of the limb of a pupating insect after 
a particular injury. Hence it seemed desirable to obtain a number 
of cases of the results of particular injuries in particular instars, 
especially as Newport’s cases were too few to permit any general 
conclusion being arrived at. I am indebted to Miss F. Durham for 
kindly placing at my disposal a large number of caterpillars of 
Samia ailanthus which were being reared in the Balfour Laboratory, 
Cambridge, in 1899 and 1900. The results were unfortunately 
somewhat limited, in consequence of the very large number of 
failures to emerge from the pupa, an event which had apparently 
nothing to do with the mutilations inflicted, for, as frequently 
happens under artificial conditions, the mortality was very high in 
the pupal state among the whole set of larvae in the laboratory. 
The experiments made were as follows. 
{A) Instar of body-length 2*0 to 2 5 cm. and of pale yellow 
colour turning to white. This is probably the instar but one 
before pupation. The injury inflicted was amputation of the third 
leg in its basal joint by scissors. Unfortunately only four imagos 
were obtained. The imaginal leg was well developed as regards 
femur and tibia, but in one case the tarsus was 3-jointed and in 
the other three 4-jointed, and in only one case (one of the 
4-jointed tarsi) were the terminal claws well developed. In the 
other three they were entirely absent, and the tarsal joints were 
not well formed though their articulations were distinct. In one 
of those with a 4-jointed tarsus the pupal period was 300 days 
(August to July) and in the other two 63 days (August to October), 
while the case with a 3-jointed tarsus was 307 days in pupa. The 
single case in which the claws were developed was one of the 
63 days’ pupas. Hence, though the number of cases is far too 
small for certainty, there is a suggestion that the length of time 
spent in pupa does not affect the degree of regeneration. 
(. B ) Instar of body-length 3*5 to 4*0 cm., and spinning about 
8 days after mutilation, so that probably the instar was the one 
which pupates, though I was unable to ascertain this point with 
certainty. The injury was amputation of the posterior leg in the 
basal joint. The average number of days spent in pupa was 61. 
Eleven imagos were obtained, and the leg was regenerated in all, 
though in a very variable manner. The femur was well developed 
in about half the cases, and stunted in the others. Tibia and 
tarsus were sometimes distinguishable, but the tibia and femur, 
and tibia and tarsus respectively were apparently fused together 
in certain cases, while the tarsus when recognisable had never 
more than four joints. In about half the cases the claws were 
more or less distinctly suggested, as was also a terminal lobe 
apparently representing the palpal apparatus. 
