74 



SCIENCE-GOSSIP. 



[April 1, 1865. 



THE CABBAGE BUTTEHELY AND ITS 



METAMORPHOSES. 



by professor a. de quatrepages. 



(internal phases.) 



"E sliall now describe in a few words the being 

 produced from the little worm which sprung 

 from the Tieris' q^% (page 33). 



The body, which is entirely clothed with hairs per- 

 ceptible to the nalced eye, consists of three segments, 

 which are separated from each other by well-marked 

 constrictions ; these three are : the head, the chest 

 or tJiorax, and the belly or ahdomen. The head is 

 small, and has attached to it in front two long, horny, 

 jointed, club-shaped feelers, or anienncB, which had 

 no existence in the caterpillar. The little simple eyes 

 are still present ; but in addition, a large round mass 

 with a trellised surface may be seen on each side. 

 These masses are the compound eyes, each facette of 

 which is a true organ of vision ; and since, according 

 to the calculations of several naturalists, there are 

 no less than thirty thousand of these facettes, it 

 follows that the animal has this enormous number of 

 distinct eyes. The mouth, which now, instead of 

 being used for division and mastication, is only em- 

 ployed for suction, is admirably adapted to its new 

 office. We can hardly find a trace of the upper and 

 lower lips or the mandibles. The jaws have been 

 immensely elongated ; their horny tissue has disap- 

 peared, and flexor and extensor muscles have been 

 developed in its place. Each jaw is penetrated by 

 nerves and tracheae, and is grooved deeply on its inner 

 surface. These organs, when placed side by side and 

 soldered to each other, constitute a sort of tube twice 

 as long as the whole body, and continuous with the 

 mouth. Erom having been organs of mastication, 

 they are now converted by this process of fusion 

 into a proboscis, which the insect rolls or unrolls at 

 wUl, and which can penetrate the deepest calyx and 

 allow it to suck up the juices of the flower as per- 

 fectly as if a syphon had been employed. 



The chest or thorax bears the legs and wings. 

 The first correspond to the horny feet of the cater- 

 pillar, but are very unlike them in appearance. The 

 limbs of the caterpillar were short and massive, 

 those of the butterfly are long and slender. Besides, 

 their structure is entirely difi"erent. In the butter- 

 fly's limb there are five distinct parts, and the last 

 or tarsus is itself composed of five joints and a pair 

 of booklets. The four wings are attached in pairs 

 to each side of the back. Each one is united to the 

 solid structures through the intervention of a chain 

 of horny pieces, connected together by strong liga- 

 ments and supplied with powerful muscles, and to 

 these are due the suppleness and force which are 

 exhibited in the movements of flight. Erom this 



basal portion spring four main nervures, which 

 diverge from each ottier, and by their ramifications 

 support the wing-membranes, which are thus stretched 

 upon a horny frame. Notwithstanding their solid 

 appearance, these nervure-s are really hoILow in their 

 interior, and are pierced by tracheee, or air-tubes, 

 which extend almost to their extremities. More- 

 over they are covered by two exquisitely delicate, 

 transparent membranes, which, firmly united to- 

 gether, clothe the upper and under surfaces. It is 

 to these that the little scales are attached which 

 give the peculiar colours to this and other butter- 

 flies, being implanted in the membrane somewhat in 

 the same manner as a bird's feathers are implanted 

 in its skin. The caterpillar did not present the 

 slightest trace of these wings or their appendages. 



The abdomen, which corresponds to the hinder 

 portion of the caterpillar's body, has lost all \i^ false 

 feet ; but with that exception has undergone very 

 little alteration. The general form has been slightly 

 modified, the colour is no longer the same ; but the 

 abdomen is invariably divided into seven rather 

 distinct rings. 



These moultings, metamorphoses, and alterations, 

 although apparently occurring spasmodically, do not 

 do so in reality. Beneath the veil of skin, which 

 will be thrown ofp in course of time, even within 

 those parts which will eventually disappear or be 

 transformed into others, the new integument is 

 being gradually formed; the general plan of the 

 future animal is being drawn out, and the various 

 organs which will afterwards be required are being 

 organized. The old garment alone is cast ofl', both 

 at the period of moulting and of metamorphosis. If 

 we cautiously detach the old but still vital skin, a 

 few days before the moulting takes place, we may 

 see its successors lying beneath it. By doing the 

 same with the caterpillar, a few days before it passes 

 into the chrysalis condition, we shall discover the 

 rudimentary wings and antennae. If at this period 

 we cut off the little scaly feet, we shall find that, 

 when the butterfly emerges from the case, its legs 

 will be imperfect. 



Laying aside the internal changes which we have 

 already alluded to, we shall confine ourselves to the 

 study of the metamorphoses of some of the large 

 apparatus, and more especially of the digestive tube 

 and nervous centres. 



The digestive apparatus which this caterpillar 

 presents when it first springs from the egg, and even 

 when it commences its transformation, is very simple 

 in character. The alimentary canal begins as a very 

 short and wide cesophagns, and ends in an intestine, 

 somewhat of the same kind, but which can hardly 

 be said to consist of two regions. Between these 

 organs we find a stomach disproportionately large, 

 Avhich fills almost the entire cavity of the body. In 

 addition to these, two salivary glands, composed of 



