246 LECTURE XVIII. 



both the antennae had been cut off, moulted a fortnight after the 

 operation, and then acquired two new but shorter antennae : the 

 legs and prolegs of caterpillars are said to be reproduced in like 

 manner after one or two moultings. 



The passive and, as it were, embryonic condition to which most 

 insects (Coleoptera, Lepidoptera, Hymenoptera, Diptera, many Neu- 

 roptera) return when, after an active larval life, the organising energies 

 again superinduce the processes of development upon those of mere 

 growth, is called the pupa state. The chief modifications of the pupa 

 have already been explained in relation to the terms coarctate, 

 obtected, incomplete, by which they were designated by Linnaeus. 



Some pupae are protected only by the exuvial skin of the preceding 

 stage, and have been termed " naked ; " others repose in cases or 

 " cocoons," artificially prepared by the larva. The valuable silken 

 cocoons of the larva of the Bombus mori, called, par excellence, the 

 " silkworm," are familiar examples of pupal chambers. In this 

 cocoon * of a larger Lepidopterous insect ( Oiketicus Kirbyi), the 

 larva, by one of those marvellous prescient instincts which give so 

 much interest to entomological enquiries, covers the close and thick 

 web of fine and soft silk which it has prepared for its pupal repose 

 with a strong outer defence of portions of twigs irregularly bound 

 together by silken filaments : thus suspended to a branch of the tree, 

 it deceives and escapes the attacks of predatory insectivorous birds. 

 The pupae whose cocoon remains partially open, as in Saturnia and 

 Phrygaiiea, are usually called " guarded " {pupce custodiat^). 



All pupae which are placed in dark situations are colourless, or 

 of a yellowish white, and become darker when exposed to the light. 

 The pupae of most butterflies, which are suspended in open day, 

 are of a green or yellowish brown colour : some are speckled wath 

 glittering spots of golden hue, either natural or produced by the 

 attacks of parasitic insects ; and such pupae have obtained the name 

 of " chrysalis " and " aurelia." 



The active pupae of Orthoptera and Hemiptera are called 

 " nymphs." These insects, which are also said to have semicomplete 

 pupae, and to undergo an imperfect metamorphosis, are subjected, 

 as I trust I have already proved, to the same law of repetition or 

 analogy which is expressed so conspicuously in insects to which alone 

 a perfect metamorphosis has usually been attributed : for, although 

 moulting be no metamorphosis, even when accompanied, as it usually 

 is in insects, with a certain change in the form of the body, yet the 

 course of the development of those insects which, after exclusion 



* No. 3073. 



