IIT PROTECTIVE RESEMBLANCES AMONG ANIMALS 51 
case with many birds, the eggs and young of which are 
especially obnoxious to danger, and we find accordingly a 
variety of curious contrivances to protect them. We have 
nests carefully concealed, hung from the slender extremities 
of grass or boughs over water, or placed in the hollow of a 
tree with a very small opening. When these precautions are 
successful, so many more individuals will be reared than can 
possibly find food during the least favourable seasons, that 
there will always be a number of weakly and inexperienced 
young birds who will fall a prey to the enemies of the race, 
and thus render necessary for the stronger and healthier 
individuals no other safeguard than their strength and activity. 
The instincts most favourable to the production and rearing 
of offspring will in these cases be most important, and the 
survival of the fittest will act so as to keep up and advance 
those instincts, while other causes which tend to modify 
colour and marking may continue their action almost un- 
checked. 
It is perhaps in insects that we may best study the varied 
means by which animals are defended or concealed. One of 
the uses of the phosphorescence with which many insects are 
furnished is probably to frighten away their enemies; for 
Kirby and Spence state that a ground-beetle (Carabus) has 
been observed running round and round a luminous centipede 
as if afraid to attack it. An immense number of insects have 
stings, and some stingless ants of the genus Polyrachis are 
armed with strong and sharp spines on the back, which must 
render them unpalatable to many of the smaller insectivorous 
birds. Many beetles of the family Curculionide have the 
wing cases and other external parts so excessively hard, that 
they cannot be pinned without first drilling a hole to receive 
the pin, and it is probable that all such find a protection in 
this excessive hardness. Great numbers of insects hide them- 
selves among the petals of flowers, or in the cracks of bark 
and timber; and finally, extensive groups and even whole 
orders have a more or less powerful and disgusting smell and 
taste, which they either possess permanently, or can emit at 
pleasure. The attitudes of some insects may also protect 
them, as the habit of turning up the tail by the harmless 
rove-beetles (Staphylindide) no doubt leads other animals 
