Mr Brindley, Regeneration in Samia ailanthus. 461 



(G) The last larval instar immediately before pupation, and all 

 cases had spun by next morning. (Amputation during spinning 

 seemed to disturb the larvae very slightly, they almost immediately 

 resumed the process of enclosure in the leaf selected, and in no 

 case did mutilation seem to delay the act of pupation.) The injury 

 was amputation of the basal joint of a posterior leg. Twenty- 

 seven iinagos were obtained, after a pupation averaging about 

 36 days. The injured leg was usually a flatfish stump, and in 

 the majority of cases there was a projection from this, so that the 

 new growth may possibly be regarded as a femur plus an out- 

 growth representing tibia and tarsus. In only three cases was 

 there a clear suggestion of a tarsus, and in one of these it seemed 

 to consist of four joints. There was in no case any indication of 

 the claw apparatus. 



(D) The instar as in (0), but the injury was amputation of 

 a posterior leg in the second (or middle) joint. Eighteen imagos 

 were obtained, and the injured limb was better formed than in 

 (0). The femur was usually very short and broad, but in nearly 

 all cases it seemed possible to distinguish tibia and tarsus. In 

 two or three cases the apparent tarsus was not divided into joints, 

 but in most one or two articulations were more or less indicated. 

 In one case only were both the terminal claws well formed. 



It must be understood that the above interpretations of the 

 regenerated limb claim only an approximate accuracy, as though 

 the larva from its large size is an easy one to injure in exactly 

 the desired manner, the imaginal legs are so covered with hairs 

 that there is often much difficulty in making out the articulations, 

 especially as the regenerated limb is always dwarf and liable to be 

 broken in attempts to remove the hairs by brushing. But the 

 observations made may be taken as at least emphasizing the great 

 variability of result arising from apparently the same degree of 

 injury, and as confirming the statements of Newport and Chapman 

 in this respect for other Lepidoptera. The want of uniformity of 

 result stands out in great contrast from what is known in the case 

 of an insect with "direct" development; e.g. in Stylopyga (Peri- 

 planeta) orientalis out of several thousand legs bearing the charac- 

 teristic 4-jointed tarsus of regeneration, only 8 were found with 

 the tarsus at all malformed. There is much suggestion that the 

 mechanism of regeneration is less highly specialised in an insect 

 whose post-embryonic development includes metamorphosis than 

 in one which proceeds by simple ecdyses to maturity. In this 

 connection it is natural to remember the greater liability of the 

 long legs of an orthopterous form to accidental injury compared 

 with the short legs of the lepidopterous larva, and the possibility 

 that a more specialised mechanism of reproduction has arisen in 

 the case of greater need for such. 



