LEPIDOPTERA. 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 
fréze. When the silkworm has just moulted it eats little, but the 
time very soon arrives when it eats with extraordinary avidity. 
It is indeed insatiable. The /réze of the last age is called the 
grande fréze. 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 
becomes as transparent as a grape. It is now said to have reached 
its maturity. Upto 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 métres long. 
* One gramme = 15,4325 er. troy. 
Q 2 
