98 
INTRODUCTION. 
closely gummed, that had both ends been similarly 
closed, its egress would have been impracticable ; 
it finds, however, no difficulty in forcing its way 
through the aperture of a sort of reversed funnel, 
formed of converging threads that res^iily yield to 
pressure from within. But an objection will here 
probably strike you. You will ask. Is not this 
facility of egress purchased at too dear a rate? 
Must not a chrysalis, in an open cocoon, be exposed 
to the attacks of those ichneumons of which you 
have said so much, and of numerous other enemies, 
which -will find adinittancc through this vaunted 
door ? Our caterpillar would seem to have foreseen 
your dilemma; at least, under heavenly guidance, 
she has guarded against the danger as effectually as if 
she had. If you cut open the cocoon longitudinally, 
you wiU see that within the exterior funnel-shaped 
end, at some distance, she has framed a second funnel, 
composed of a similar circular series of stiff threads, 
which, proceeding from the sides of the cocoon, con- 
verge also to a point, and form a sort of cone exactly 
like the closed peristome of a moss ; or, to use a 
more humble though not less apt illustration, like 
the wires of certain mouse-traps. In this dome not 
the slightest opening is left, and from its arched 
structure, it is impenetrable to the most violent 
efforts of any marauders from ndthout; whilst it 
yields to the slightest pressure from within, and 
allows the egress of the moth with the utmost 
facility. "When she has passed tluough it, the 
elastic threads resume their former position, and 
1 
