^9 [ 175 ] 



I'lie silk-caterpillar has sixteen feet. The three first pair are scaly and, 

 hard, and placed under the three first rings, one on each side. The 

 next two rings are destitute of feet. The four succeeding rings have 

 ^;ach two feet. These are soft and membranous, and swell, contract, 

 and expand, at the will of the insect. The next two rings are with- 

 out feet; the last ring has two feet. The extremities of the twelve 

 membranous feet, are furnished with hooks, or claws, the number 

 of which, according to the accurate Malphigi, are forty* in number in 

 each foot. They are of different sizes, and are placed in double and 

 equi-distant rows. The extremities of the six first feci, consist of 

 curved nails, or hooks, which enable the caterpillar to hold to the spcfi 

 to which it has been pushed by the contractions of the posterior 

 rings. These feet are the envelopes of those wliich appear in the 

 moth. The others remain with the cast off skin of the caterpillar. 



On the last ring but one, is placed a small horn, if that can deserve 

 thi^ name, says Reaumur, which is used neither as a weapon of attack 

 nor defence. This accurate naturalist acknowledges his inability to 

 point out its use. The head of the caterpillar is formed of two scaly 

 spherical pieces, which do not touch, but leave a triangular space be- 

 tween them. On each side of these pieces, and in front, six or seven 

 black spots, arranged in a circle, may be seen: these are the eyes. The 

 opening between these two pieces, below and in the forepart, is the 

 mouth. It is armed with two parallel jaws, and with teeth, which 

 move horizontally when the insect eats. The spinnaret, or silk hole, 

 is near the summit of a pyramidal substance, occupying the middle of 

 the lower lip, and terminates in a little papilla of a black form, from 

 the point of which the silk filament issues that forms the cocoon. The 

 canal which receives the aliment, proceeds, in a straight line, from the 

 mouth to the vent, and is of different capacities, analogous to the gul- 

 let, the stomach, and intestines, of animals. The vessels in which the 

 silk is formed, consist of two parallel tubes of the same size, which 

 are so extremely delicate near their termination, as to appear to unite 

 in one tube; but, by immersing and hardening the insect in spirits of 

 wine, Reaumur! found that they continued separate to their ends, and 

 that he could take them out entire: they are about one foot in length. 

 The use of the microscope confirmed the structure: for, by the help of 

 this apparatus, he discovered that the fibre of silk, minute as it is, in-- 

 stead of being round, as it would be if it proceeded from one vessel, 

 had more breadth than thickness, and that, in the middle of each fibre, 

 there was a kind of furrow, giving the appearance of two flattened 

 cylinders glued together. In some threads, he even saw the separa- 

 tion, or forks, at the end of the threadt From the contracted nature 



* De Bombycibus, p. 9; Malphij;-i Opera Lonciini, 173". 



\ Memoire sur insects, p. 147, 1'avis, 4to. 17o4. 

 • 4 Memoire, p. 499. In this admirable work, Reaumur has kIiowii this confirmation 

 of the silk thread in mag-nified fi^^ures. Plate 5, fig. 4; plate 32, fig. 13, 14, 15; 

 plate 33, fig. 1, 2, 3. Leewenhoek had, many years previously, demonstrated this 

 structure by the microscope. Lyonct, however, questions the accur^jcy ofbotii, and 

 insists that both silk tubes unite before they reach the orifice. Traite Anatomaque 

 de la Chenille, &c. p. 5.5. A la Haye, 1763. 



