CLASS INSECTS. 427 



and with some care they may be thus preserved for a suffi- 

 ciently long time without becoming deteriorated. In order 

 that incubation commence, and that the larvae appear or un- 

 fold themselves, it is necessary that the eggs be placed for 

 some time under the influence of a temperature of at least 

 15 or 16 Cent. (59 Fahr.). After having experienced eight 

 or ten days of increasing heat they become whitish, and soon 

 after the larvae begin to come forth. These small animals 

 at the moment of their birth are only about a line and a 

 quarter in length. Their body (Fig. 449) is elongated, cylin- 

 drical, annulated, smooth, and generally of a greyish colour. 

 At its anterior extremity may be distinguished a head, formed 

 by two kinds of hard scaly caps, on which may be remarked 



Fig. 449. Silkworm. 



black points, which are the eyes. The mouth occupies the 

 anterior part of this head, and is armed with strong jaws. 

 The three following rings have each a pair of small scaly 

 limbs, and represent the thorax. Finally, the abdomen is 

 very large, and has no limbs on the first two segments, but 

 is furnished posteriorly with five pairs of fleshy tubercles, 

 which resemble stumps, and which constitute so many limbs. 

 In the south of France silkworms are called magnans, and 

 hence the name of magnanerie given to the establishments 

 in which they are reared. The first care they require after 

 their birth is to separate them from their cocoons, and to 



