426 ZOOLOGY. 



the interior of its body an active labour, the result of which 

 is the complete development of all its organization. Its in- 

 ternal parts soften, and by little and little assume the form 

 which they are afterwards to maintain. The various organs 

 with which the adult animal is to be provided become developed 

 under the envelope concealing them, and when this evolution 

 is finished, it frees itself of this kind of mask, unfolds its 

 wings, which soon acquire consistence, and becomes a perfect 

 insect. 



Fig. 448. Papillon Machaon ; Swallow-tailed Butterfly. 



532. As an example of these metamorphoses, we could 

 not choose a better than that of the bombyx of the mulberry ; 

 for this insect, in the state of a larva, is for us of immense 

 interest. It is the silkworm, the rearing of which contributes? 

 so powerfully to the agricultural prosperity of our southern 

 provinces, and whose products support so many wealth-pro- 

 ducing employments. This insect, originally from the northern 

 provinces of China, was introduced into* Europe only in the 

 sixth era. Some Greek missionaries brought the eggs to 

 Constantinople during the reign of Justinian, and at the 

 epoch of the first Crusades its culture spread into Sicily and 

 Italy ; but it was only in the time of Henry the Fourth that 

 this branch of agricultural industry acquired some importance 

 in our southern provinces, of which it forms, at the present 

 day, one of the principal sources of wealth. 



The eggs of the mulberry bombyx are known to agricul- 

 turists by the name of seed of the silkworm. When they 

 have been exposed to the air they have an ashy-grey tint, 



