May 1. 18^4.^ 



KNOWLEDGE. 



105 



ri&. 2.— Hooks 

 at end of chrysalis 

 of Red Admiral 

 Butterflr. 



the preceding, so that a conical mass is formed. Then 

 the hooks of the last pair of prolegs are entangled in the 

 mass, and the caterpillar swings down into a vertical 

 position. It has now to cast its skin, in 

 order to appear as a chrysalis. The head 

 is bent round in a curve and after a 

 while the skin splits along the back, and 

 the contained chrysalis appears through 

 the opening. By various contortions it 

 manages to push the old skin gradually 

 backwards towards the point of suspen- 

 sion. The tail of the chrysalis is not 

 yet attached to the support, though the 

 old skin is ; but before the skin is pushed 

 quite off, it is necessary for the chrysalis 

 to secure itself. This it does by working 

 itself gradually upwards by means of the still partially 

 investing skin, and stretching out its tail till it can reach 

 the button of silk. The tail is provided with a large 

 number of hooks (Fig. 2), and by means of these the 

 chrysalis fastens itself to the silk, and hangs securely while 

 the skin is completely pushed away. 



The white butterflies and their allies, as well as the 

 swallow-tails, make a more elaborate arrangement. For 

 some reason or other, they elect to lie parallel to the 

 surface of support instead of hanging freely suspended. 

 They therefore add to the tail button a thin loop round 

 the anterior part (Fig. 3), fastened on each side to the 

 object of support, but not in any way 

 adhering to the chrysalis, which there- 

 fore lies free in the loop. The loop is 

 made either by the caterpillar bending 

 backwards and running its threads 

 from side to side over its body, or by 

 constructing the loop first and after- 

 wards getting into position. 



The ancients were sorely puzzled as 

 to the origin of the silk of commerce. 

 For many centuries it reached Europe 

 only as a raw product, or a manu- 

 factured article coming from the East, 

 where it was cultivated, a region which 

 to an average European might as well 

 have been, for aught he knew about it, 

 in another world. Thus, never having 

 seen the thing in its natural condition 

 as produced by the silkworm, they 

 trusted to rumour for the explanation of 

 its origin, and, as usual, rumour grotesquely mangled the 

 tale as it travelled from mouth to mouth many times over. 

 Silk had some sort of connection, it was understood, with 

 the animal kingdom and some with the vegetable, but 

 what was the precise share of each was by no means clear. 

 Certain insects and trees had a kind of partnership in 

 its production, but only the vaguest notions were current 

 in many places as to the sort of insects and trees that 

 were between them responsible for the lovely product. 

 Perhaps we cannot do better, in order to show the 

 absurdity of the ideas held on this subject even by 

 educated people some eighteen centuries ago, than quote a 

 passage from the naturalist PUny, who flourished during 

 the golden age of Latin literature ; and as the crudity of 

 the ideas will find a better match in an antique English 

 version than in the literary language of the nineteenth 

 century, we will adopt the rendering of an old translator. 

 The passage is as follows : "They build their nests of 

 earth or clay, close sticking to some stone or rock, in 

 manner of salt ; and withall so hard, that scarcely a man 

 may enter them with khe point of a spear. In which they 



of 



FlO. 3.— Chrysalis 

 Swallow-tail But- 

 tertty, suspended by 

 button and loop. 



make also wax, but in more plenty than bees ; and after 

 that, bring forth a greater worme than all the rest before 

 rehearsed. These flies engender also after another sort 

 namely, of a greater worme or grub, putting forth two homes 

 after that kind : and these be certain canker-wormes. Then 

 these grow afterwards to be Bombilii, and so forward 

 to Necydah : of which in six months after come the 



silke-wormes Bombyces It is commonly said, 



that in the Isle Cos there be certain silkwormes engendered 

 of flowers, which by the meanes of rain-showers are 

 beaten downe and fall from the cypres tree, terebinth, 

 oke and ash ; and they soon after doe quicken and take life 

 by the vapor arising out of the earth. And men say, that 

 in the beginning they are like unto little butterflies, naked, 

 but after a while (being impatient of the cold) are over- 

 growne with haire ; and against the winter, arme themselves 

 with good thick clothes ; for being rough-footed, as they are, 

 they gather all the cotton downe of the leaves which they 

 can come by, for to make their fleece. After this, they 

 fal to beat, to felt and thicken it close with their feet, then 

 to card it with their nailes ; which done they draw it out 

 at length, and hang it betweene branches of trees, and 

 so kembe it in the end to make it thin and subtill. When 

 al is brought to this passe, they enwrap and enfold them- 

 selves (as it were) in a round bal and clew of thread, and 

 so nestle within it. Then are they taken up by men, put 

 in earthen pots, kept there warme, and nourished with 

 bran, untill such time as they have wings according to 

 their kind ; and being thus well-clad and appointed, they 

 be let go to do other businesse." 



With such a ridiculous collection of nonsense had the 

 elite of Eoman society to be content, if they wished to know 

 anything of the origin of the soft and brilliant fabrics 

 which they so much prized as a novel article of clothing. 

 It is plain that the author writes simply from hearsay, 

 and has jumbled up together notions derived from different 

 insects and embellished them with freaks of the imagina- 

 tion. And yet there was nothing so very extraordinary in 

 the production of silk by silkworms. The counterpart of 

 the process was going on every season in wild nature in 

 hundreds of places in the coiintry districts all round the 

 Western folk as well as in the remoter regions of the far 

 East ; and one would have thought that they might have 

 recognized enough resemblance between the cocoons of the 

 wild Lepidoptera of their own regions and the silk of 

 commerce to have made a nearer guess at the origin of 

 the latter, had they but had eyes to observe more carefully 

 what was going on in the woods and fields close to their 

 own doors. Another account was even more ludicrous, 

 for it was gravely stated that silk was the entrails of a 

 spider-like creature which was fed for four years on a kind 

 of paste, and then with willow leaves, till it actually burst 

 with fat. 



The silk-glands of the silkworm are, as might be expected, 

 exceedingly well developed, and may be taken as the type 

 of the organs for the order at large. On opening the body 

 of a silkworm, the glands may be seen as twisted tubes 

 Ijong partly by the side of, and partly underneath the 

 stomach. Each consists of three parts. The central, which 

 is the most prominent, is a stout, yellowish tube, bent into 

 folds ; this is prolonged behind into a much-twisted but 

 narrower tube, and in front into a very fine straight one. 

 The straight tubes of the two glands unite to form a 

 common canal, which leads to the spinneret or papilla 

 placed beneath the mouth. The gummy secretion which 

 is elaborated in the lower divisions of the glands passes 

 as fine threads into the common canal, where another 

 secretion from small glands at the sides unites the two 

 threads into one, at the same time giving the combined 



