. Insect transformations . r if they were obstructed, whilst wet, they could notafterwards be set to rights. All these changes are perfected, according to Swam-merdam, by the force of the circulating fluids and theair, impelled by respiration, a fact of which, we think,there cannot be any doubt. It is very seldom, how-ever, that we can surprise insects at the precise mo-ment of their transformation, as it is for the most partvery speedily accomplished, for the whole of the pre-ceding evolutions are usually completed in ten or fif-teen minutes. It happened by mere chance, saysSwammerdam, that I
. Insect transformations . r if they were obstructed, whilst wet, they could notafterwards be set to rights. All these changes are perfected, according to Swam-merdam, by the force of the circulating fluids and theair, impelled by respiration, a fact of which, we think,there cannot be any doubt. It is very seldom, how-ever, that we can surprise insects at the precise mo-ment of their transformation, as it is for the most partvery speedily accomplished, for the whole of the pre-ceding evolutions are usually completed in ten or fif-teen minutes. It happened by mere chance, saysSwammerdam, that I observed them for the first time:one of these vermicles adhered to a stone-wall in theriver Loire, and it was so softened by the water dash-ing up against it, that it could only half perfect itschange, so that I took it jiartly free and partly yetfixed in the skin. I once afterwards saw this changein the large kind of dragon-fly {^shna?) which hadcrept to land out of a small lake, and cast its skin sit-ting in the grass.*. a, newiy-hatclied blow-fly magnified, showing (he pulpy,crumpled slate of the wings. 6, the wings dry and fully ex-panded. * Bibl. .\at., vol. i, 1-. 98. EXPANSION OF PERFECT INSECTS. 339 Some species of flies have their wings shortenedvery considerably in the pupa state by zig-zag or trans-verse folds; so that, when newly evolved, it might besupposed, iVoni their moist and crumpled appearance,that they could never become so fine, gauzy, and trans-lucent, as they are actually seen to do. This will bebetter understood from the above figures than by de-scription. ^V^e have talten the preceding examples of expan-sion of the wings from those insects in which these aremore or less transparent, and consequently the branch-ing of the tubes {nervurcs) through them is more obvi-ous than in moths and butterflies, in which the wingsare covered with feathery scales. It is, however, lessrare to see the latter transformed than the former,from the greater facility of reari
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