5S MODES OF QUITTING THE PUPA. 
their assistance also : the end of the cocoon 
(the common name for these silken cases), 
which is next the head, is the last part 
that is spun, and very thin ; resembling in 
some measure a cap or lid. Immediately 
under the moth's head there is placed 
a very small bag, filled with a liquid 
of such a powerful acid, as instantly to 
dissolve the gam by which the silky fibres 
are cemented ; and when this is softened 
the fly can easily make its way out. 
Lucy, But it must first have got out 
of the chrysalis shell, before it can get 
through this outside case ; how does it 
manage that ? 
Mother, Over that part of the moth's 
back, which is next to the head, you may 
observe, in the chrysalis, a straight line ; 
it is more strongly marked in some than 
in others, but it is always along this lin^ 
that the shell opens ; the opening is made 
by the moth's moving its head up and 
down, which enlarges the slit sufficiently 
to let the fly out. 
Very large cases however are made 
