GO [August, 



friend Mr. Buckler has apparently likewise not accounted for this 

 critical moment in his description of the transformations of Liinenitis 

 Sibi/Ua, published in this magazine, vol. iv, pp. 33-35. — Eds.] 



[Last year (Nature, vol. xv, p. 7) I communicated the result of some experiments 

 on the caterpillars of Pieris brassiccB from which it appeared that, when these are 

 artificially converted from Succincti into Suspensi by cutting the loop before the 

 exclusion of the chrysalis, a certain number (a third or fourth of the -whole) succeed 

 in attaching themselves to the silk by the hooks in the tail of the chrysalis in the 

 manner of the true Suspensi. I have repeated the experiment this year with a like 

 result, and I have also had the satisfaction of witnessing the process of successful 

 exclusion, and comparing it with that of the chrysalis of T'anessa urticce. The 

 method is essentially the same, except that the rapid and assured precision with 

 which the Vanessa chrysalis thrusts up its tail and lays hold upon the silk, is replaced 

 in Pieris by long and laborious efforts, as if the tail were just a little too short to 

 reach the silk. 



I have likewise made similar experiments with another of the Succincti — Antko- 

 charis cardamines — with the following results : — In seven instances I cut the loop 

 (and sometimes a second one) which the caterpillar had spun ; and in all the 

 chrysalis was excluded without falling down ; but in no case was the tail of the 

 chrysalis withdrawn from the jjoeket of the old caterpillar-skin, so that its 

 suspension is directly from the latter. In eleven cases in which I did not 

 interfere, only two chrysalids were excluded in the normal way, i. e., vertically, with 

 the head up, a girdle round the insect and the chrysalis-tail withdrawn from the old 

 skin and attached immediately to the silk on the stem of the plant. In three other 

 cases in wLicli a loop was spun by the caterpillar, the chrysalis seems to have turned 

 upside-down during exclusion, tlie tail being now uppermost, the loop twisted, and 

 the hooks fastened in loose silk upon the plant-stem. Six caterjriillars either spun no 

 loop at all or one so insufficient that they became Suspensi of themselves before 

 exclusion began, and where all but one (which fell down) successfully excluded in this 

 position— the tail of the chrysalis, however, being still retained witliin the pocket of 

 the old skin. 



The most interesting and curious point in the transformation of a caterpillar of 

 the Suspensi is the manner in which the newly-excluded chrysalis is kept from 

 falling, while its hook-furnished tail is being withdrawn from the old skin of the 

 caterpillar and made fast in the cone of silk to which the latter was attached. I am 

 ignorant whether any other explanation of this process has been given than that, I 

 believe, originally communicated by Re'aumur and detailed in Xirby and Spence, 

 vol. iii, pp. 208, 209, and repeated in such recent works as Figuier's " Insect World," 

 from the English edition of which work by Prof. P. Martin Duncan (1872), p. 148, 

 I quote the following account of the pupation of Vanessa vrticce : — " But here comes 

 the culminating point, the most difficult part of the operation. The chrysalis, which 

 is shorter than the caterpillar, is at some distance from the silky network to which it 

 must fix itself ; it is only supported by that extremity of the caterpillar's skin which 

 had not been split open. It has neither legs nor arms, and yet it must free itself 

 from this remaining part of the skin, and reach the threads to which it is to suspend 

 itself. The stqyple and contractile segments of the chrysalis serve for the limbs 



