Mr Brindley, Regeneration in Samia ailanthus. 459 



instances of homoeosis, there is among Arthropod animals a high 

 degree of constancy of form and feature in the regeneration after 

 particular injuries; i.e., if regeneration occurs at all, the new limb, 

 though at least at first of small size, is well-formed and ap- 

 parently an efficient organ, and in some cases it is known that 

 the mechanism of regeneration is so specialised that neither the 

 stage at which injury was inflicted or the degree of injury, so far 

 as it is possible to gauge the latter accurately, make no profound 

 difference to the form assumed by the regenerated limb. The 

 above statements however appear to receive but partial support 

 from those insects in which the post-embryonic development 

 includes complete pupation, though the number of experiments 

 hitherto made is very small and these have been confined to the 

 Lepidoptera. Newport amputated the 3-jointed larval leg in its 

 basal or second joint just before pupation and described the results 

 for about 15 cases. In the imagos there was much variation in 

 the condition of the injured limbs. In all cases femur, tibia, and 

 tarsus could be distinguished, but the number of tarsal joints varied 

 considerably. In all, however, the terminal claw of the tarsus was 

 present. This fact and the drawings which illustrate his paper 

 suggest that the reproduced tarsus in all these cases should be 

 regarded as representing the whole of the normal tarsus, rather 

 than for instance that a 3-jointed tarsus should be considered as 

 equivalent to three particular joints of the normal tarsus. How- 

 ever this matter be regarded, it remains that the tarsus is 

 sufficiently represented to bear the normal termination, the claw : 

 so that his observations illustrate the tendency, seen so widely in 

 the regenerated limbs of Arthropods, to produce the proper 

 terminal structures, though normality in the number of joints 

 may be absent. Chapman has extended the range of the enquiry 

 by amputation of the larval leg in the penultimate instar before 

 pupation, and secured uniformity of method by always amputating 

 the basal joint and performing the operation immediately after an 

 ecdysis. In the imago the claw apparatus is present in the six or 

 seven cases this author describes and figures, though there is 

 considerable variation in the number of joints, and in one instance 

 the imaginal limb is only two rounded joints bearing a dwarf claw. 

 Dr Chapman informs me that he has made several hundred muti- 

 lations in different instars with the view of observing the progress 

 made from stadium to stadium, and it is to be hoped that the 

 results of these, the first at all extensive experiments, will be 

 published by him, as to my great regret I have so far had no 

 opportunity of taking advantage of his very kind suggestion that 

 I should examine his material myself. 



The following observations were made while I was unaware 

 that Dr Chapman was examining the same subject, and were 



