Checks on Increase 
moonlight these creatures were really not at all 
conspicuous, indeed that they were obliteratively 
coloured. In other words, a totally wrong ex- 
planation of their colouring would be given and 
accepted. It is our belief that many of the 
explanations put forward and accepted of the 
colouration of existing species are wide of the mark. 
As all bee-keepers are aware, the disease 
known as foul-brood works more havoc among 
their bees than all the insectivorous creatures 
put together. 
Similarly throat disease among wood-pigeons 
does more towards keeping their numbers down 
than all the efforts of predacious birds. 
A check on multiplication not mentioned by 
Darwin is that which is sometimes imposed by 
the individuals of the species on one another. 
Thus, in some animals, as, for example, the 
hyzena, the male occasionally devours his own 
young ones. 
A check of a similar nature results from the 
habit which the Indian House Crow (Corvus 
splendens) has of interrupting: the pairing opera- 
tions of its neighbours. 
We are now in a position to sum up briefly 
the more important requisites for success in the 
struggle for existence. 
These are not so much specialised structure as 
courage, a good constitution, mental capacity and 
prolificacy. 
z 353 
