LEPIDOPTEEA. 227 



At each of these periods in the life of the silkworm may be 

 remarked a physiological fact to which has been given the name of 

 Jreze. When the silkworm has just moulted it eats little, but the 

 time very soon arrives when it does so with extraordinary avidity. 

 It is indeed insatiable. The freze of the last age is called the 

 grande freze. It takes place about the seventh day. During 



Fig. 208. Fifth age. 



this day worms, the produce of thirty grammes* of eggs, consume 

 in weight as much as four horses, and the noise which their little 

 jaws make resembles that of a very heavy shower of rain. It is 

 at the end of this stage that the insect prepares the shelter in 

 which is to be brought about its metamorphosis into a chrysalis. 



A little while before this it ceases to eat, turns yellow, and be- 

 comes as transparent as a grape. It is now said to have reached 

 its maturity. Up till this moment the worm had never tried to 

 leave its litter. It lived a sedentary life, and never thought of 

 wandering away from its food. Now it is seized with an imperious 

 desire for changing its quarters. It gets up, it roams about, 

 and moves its head in all directions to find some place to cling 

 on to. It walks over everything within its reach, particularly 

 over those obstacles which are placed vertically. It aspires, not 

 to descend like the heroes of classic tragedy, but to rise. It is for 

 this reason that this period of the silkworm's life has received 

 the name of the mounting or ascending season. It now looks for 

 a convenient place in which to establish its cocoon. Every one 

 has remarked how the animal sets to work to accomplish its 

 task. It begins by throwing from different sides threads destined 

 for fixing the cocoon ; this is what we call refuse-silk. The 

 proper space having been circumscribed by this means, the worm 

 begins to unwind its thread, a continuous thread of about a 

 thousand yards long. 



* One gramme = 15,4325 gr. troy. 

 Q2 



