THE SILK WORM MOTH. 133 



worms now weigh an ounce. The fifth age of the 

 caterpillar comprises nearly a third part of its brief 

 existence, and has been described by an enthusiastic 

 writer on the subject as the happiest period of its 

 life, during which it rapidly increases in size, and 

 prepares and secretes the material which it is about to 

 spin. When the Silk Worms are fully grown, and 

 have arrived at that period \vhen they finally reject 

 food, six of them make up the weight of an ounce. 

 They have, therefore, since their last change, again 

 added to their weight six fold. Thus it will be seen 

 that the insect has multiplied its weight more than 

 nine thousand fold. 



It is worthy of remark, that, when the moth has 

 assumed its perfect state, it does not think of using 

 its wings like other winged insects, for it never 

 betakes itself to aerial excursions, and seldom moves 

 beyond a few inches from the spot where it was 

 hatched. 



It will be readily imagined, that this remarkable 

 insect occupies a place in our volume, not from per- 

 sonal beauty, but from the importance of its labours 

 in a mercantile point of view, and its utility to man- 

 kind. We should here have followed up an account 

 of the animal by a history of silk ; but as that is more 

 a statistical than natural history subject, it would 

 interrupt the plan of the present portion of the work, 

 and we shall, therefore, transfer it to the close of the 

 descriptions. 



