June, 1897.] 
Webster : On Protective Mimicry. 
75 
but the object of all of these efforts would be the protection of life, by es¬ 
caping capture and securing food to sustain that life, and the most suc¬ 
cessful would be the most apt to survive. 
But have we not had, during all of this time, a consciousness of pos¬ 
sible destruction and volition in the efforts put forth to get out of the way 
of an enemy in pursuit ? Do not these, in fact, coexist with animation 
itself; and does not their presence really afford natural selection the 
primary foundation with which to begin the development of certain 
characteristics, and perfect such to an extent necessary to the life of an 
organism ? 
Another kind of phenomena, commonly termed feigning death, also 
comes within the scope of this paper, and includes such species as, when 
they are alarmed, either fall to the ground or assume certain rigid po¬ 
sitions while attached to plants, or both, so as to appear either dead or 
like some lifeless object. Many insects, when disturbed, will draw up 
their legs and falling down remain perfectly still and rigid until the 
supposed enemy has passed on. Very many of our beetles do this, and 
because of our common opossum Didelphys virginiana , taking a similar 
course in its attempts to escape death, the action has been vulgarly 
termed “playing possum.” Species belonging to the Coleopterous 
genera Chlamys and Exema , however, are shaped and colored so as to 
almost exactly represent the excreta of caterpillars, and when feeding, 
if disturbed, will drop to the ground if not caught by the leaves of the 
plant upon which they are feeding, and as they lay perfectly still, may 
be unrecognized by even fairly good entomologists. But, even the pe¬ 
culiar form and color of these insects would fall far short of protecting 
them while feeding, as their position at that time is so entirely different 
from that under which the excreta of caterpillars is usually observed; 
but, when they loose their hold, and drop to the upper surface of a 
lower leaf and either remain there or roll off and fall upon the ground, 
the deception is complete. 
The resemblance of the larvae of Geometridae, to small twigs of trees 
and shrubs is everywhere observed, and as universally excites feelings of 
delight and surprise. When disturbed, the caterpillars assume a rigid 
position, more or less transverse to the limb upon which they are lo¬ 
cated, so that their position, together with the peculiar form and color 
of their bodies, render them not easily detected. In some species, the 
form of the body is such as to closely resemble a dead twig, even to the 
buds thereon. In this case it requires the assumption of the peculiar 
and rigid position, in order to complete the deception so far as it is 
