[ 175 ] 3<i 



might be supposed, wound circularly, as we wind the thread of a ball 

 of. cotton, but backwards and forwards, in a series of zigzags, so as to 

 compose a number of distinct layers. Malphigi* distinguished six of 

 these layers; and Reaumurt suspects there is often a greater number. 

 Hence, when the cocoon is wound off, the unravelling proceeds in a 

 very irregular manner. The inside is smeared with a gum of the 

 same nature with that out of which the silk is formed. 



The construction of the cocoon is a work of three days, or three 

 days and a half. During the first day, the insect forms the exterior 

 envelope, which is merely the scaffolding, by means of which the in- 

 ner and more solid covering is constructed. On the second, it forms 

 the ball, and covers itself with silk. The third day, the insect is quite- 

 hid, and afterwards it is employed in thickening and strengthen- 

 ing the ball. Having done this, the caterpillar has to undergo a 

 second change of form, viz: into that of a chrysalis; that state in- 

 tervening between the larva, or caterpillar, and imago, or perfect 

 moth, in which its parts and organs are fully prepared, and fitted for 

 their final and complete developement in the last mentioned state. 

 This state is assumed on or about the fourth day after having spun its 

 cocoon. In this state it is quiescent, and apparently without life, but 

 all this time a new organization is internally forming. The first ope- 

 ration it performs, is to cast off the external skin, which covered it 

 in the caterpillar state, with the head and jaws attached to it. This- 

 it does in one or two days after finishing its cocoon, and, according 

 to Malphigi, in the space of one minute and ten seconds;^ who adds, 

 that the act is greatly promoted by a yellovvish fluid, discharged frora 

 the cavity of the head, which enables the outward skin the more 

 easily to slip over it, as the insect contracts and elongates. The 

 caterpillar thus stripped, is called the pupa. The exterior cover- 

 inc gradually becomes hard, while the interior remains so soft, that 

 the slightest touch will decompose it. The stomach is filled with 

 yellow mucus, which is doubtless the source of nourishment to the 

 pupa. The germs, or rudiments, of the future moth, which, according 

 to Swammerdam, may be detected even in the caterpillar, near its 

 last change, in a semi-fluid state, § gradually develop, and assume- 

 their destined form; the wings, rolled up, are lodged between the 

 second and third rings; the antenna are placed alongside of them; the 

 lc£;s are actually sheathed in legs; and when tliey have acquired a 

 proper degree of solidity, a slight inflation of the body is sufficient to 

 split the membrane which covers them. A repetition of these motions 

 enlarges the slit, and affords the moth room to escape ffom its confine- 



* Dc Bombycibus, p. 24. 



j To'.nc 1, p 498. 



i De I'lombycibiis, p. 25. 



§ To discover these, it is directed to drown the catei'])i]Iar, when about to assume 

 the pupa state, in vincg'ar, or spirits of v.ine, and to let it remain there for several 

 days, to harden the parts: or to boil it for a few minutes, then to dissect off the skin, 

 when the enc';)sed motli will appear, bqt the parts are in a different manner front 

 that in which they lie 'mi. the pupa. 



