144 THE entomologist's recobd. 



position, that no part of the imaginal leg existed, or was represented, 

 in the larval leg, except, perhaps, the tarsus. 



My position is to assert the older idea, that the three parts or 

 joints of the larval leg are femur, tibia, and tarsus, and that these 

 parts of the imaginal leg originate in those larval sections. And I 

 expected to find that a leg regenerated, Avhich ought by Gonin's 

 hypothesis to be, as regards the femur and tibia, the normal leg of the 

 imago, Avould not be so. Newport's experiments, I thinly, suffice to 

 show that my view of Gonin's position is correct, but one always likes 

 to verify these matters one's self. The few experiments I made last 

 year on this subject, were really made rather with a view to finding 

 out how to attack it than with any hope of a definite result. They do, 

 however, present enough material to yield some definite results, con- 

 firmatory of the hypotheses I have adopted, and, I think, negativing 

 that upheld by Gonin. 



The question is complicated by the many interesting facts of 

 regeneration, which would well repay further more accurate experi- 

 ments, and it is rather in their hearings on that side of the subject 

 than on that before us, that my experiments must appear so meagre 

 and inconclusive. 



My experiments consisted in removing the whole or portions of the 

 third left leg of certain larvfe. Those I used were Forthetria clispar 

 and Saturnia pavonia {carinni) . The latter are still in pupa. The results 

 I lay before you are only those of the former species. I selected these two 

 species merely because I had an abundance of eggs of each. I 

 removed only one leg (though sometimes I fear injuring others, 

 through the struggling of the larva), as interfering less with the health 

 and progress of the larvaB. One leg also enabled a comparison to be 

 made with the leg of the opposite side. I selected the third leg 

 because it is hidden in the pupa beneath the wing, and so would not 

 leave an abnormal vacancy on the pupal surface, which is often fatal 

 in pupal existence. 



I began by chloroforming my larva, with a view to proper 

 humanity, but found that chloroform inflicted much greater incon- 

 venience on the larva than to hold it firmly in the fingers and snip 

 oft" the limb. The inconvenience this caused both at the time and 

 afterwards was much less than I anticipated. I imagine that no 

 actual pain is felt in our meaning of that word. Newport gives some 

 details of the eft'ects of the operation on the health of the larva and 

 t he healing of the wounds. The preparations I show you are the two 

 third legs of the imagines, and the same portions of the larval skin 

 found with the pupa. The larval skin of Portlietria diqmr does not 

 shrivel up very much at the pupal moult, so that by soaking it in 

 ammonia for some time I have been able to vmravel it to some degree, 

 and in a few instances with very fair success. 



The specimens will, to a great extent, explain themselves. That 

 represented in pi. vi., fig. 1 may be taken first. On the right side 

 (left as mounted) of the insect, the larval and imaginal legs are 

 normal. On the left the larval leg is a mere stump, but examination 

 shows that it possesses all the parts of a complete larval leg, three 

 joints and a claw. In this case the leg was removed in an earlier 

 skin, removed to its base, and we here have in the last larval skin a 

 regenerated leg, though of very small size. The parts are all there. 



