OB, PLAIN TEACHING. 



39 



clothes), 3 ; fourth, the imago (or 

 perfect image), 4. The example 

 given, 215, is that of the silk- 

 worm (JBombyx mori). This 

 insect remains in the egg, 1, 

 during the winter, and is hatched 

 by the warmth of April or May. 

 The larva, 2, when it first emerges 

 from the egg, 1, is little more 

 than a black speck, but grows 

 rapidly, changes its skin four or 

 five times, and in about eight 

 weeks is ready to enter the pupa 

 state, for which it prepares a 

 nest of silk, called a cocoon, 5, 

 inside which it forms 

 a chrysalis, 3, and re- 

 mains in a state of 

 torpor for some time, 

 during which its wings 

 and legs are formed, 

 and it emerges as a 

 perfect moth, 4. In 216 » 

 some the chrysalis bears a 

 resemblance to the form of the 

 insect which it contains. In the 

 chrysalis of the peacock butterfly 

 [Vanessa io), 6, the wings appear 

 to be folded up underneath the 

 sides of the case, 7, while the 

 ant ennce, proboscis, and 

 aiBk legs are indicated by 

 III lines which pass down 

 III/ its centre, 8. But 

 there are some insects 

 whose metamorphoses 

 are even more remark- 

 able, since they live in 

 water during the first 

 three stages of their 

 existence, and become 

 tenants of the air in their perfect 

 condition. The female gnat 

 (Culex pipens), standing upon a 

 leaf, or a bit of stone, manages, 

 by her hind-legs, to arrange her 



eggs in the form of a little raft, 

 10. The eggs are gummed to- 



217. 



213. 



gether side by side, and they 

 float upon the water, receiving 

 the rays of the sun until the 

 embryoes are developed. Each 

 egg, 11, has a little 11 

 lid, or valve, 12, 

 through which the ^^^^^^^jfg 

 young larva escapes, - 19 « 

 12,and becomes an inhabitant of the 

 water. The larva, 13, presents a cu- 

 rious appearance, and though liv- 

 ing in the wa- 

 ter, breathes 

 air, which it 

 does by com- 

 ing to the sur- 

 face, and pre- 

 senting respi- 

 ratory tubes, 

 14, to the at- 

 mosphere. 

 The insect 

 changes its 



220. 



shape again when it assumes the 

 pupa form, and 

 by a strange 

 transformation 

 the respiratory 

 tubes previous- 

 ly attached to 

 its tail, 14, now 

 occur at its 

 head, 16. In 

 the pupa state, 

 15, it is less 

 active than as 

 a larva, 13 ; 

 remaining for long periods at 



221. 



