94 
NATUEAL SELECTION. 
Chap. IV. 
another flower or on another plant. In plants under 
culture and placed under new conditions of life, some¬ 
times the male organs and sometimes the female organs 
become more or less impotent; now if we suppose this to 
occur in ever so slight a degree under nature, then as 
pollen is already carried regularly from flower to flower, 
and as a more complete separation of the sexes of our 
plant would be advantageous on the principle of the 
division of labour, individuals with this tendency more 
and more increased, would be continually favoured or 
selected, until at last a complete separation of the sexes 
would be effected. 
Let us now turn to the nectar-feeding insects in our 
imaginary case: we may suppose the plant of which 
we have been slowly increasing the nectar by continued 
selection, to be a common plant; and that certain in¬ 
sects depended in main part on its nectar for food. I 
could give many facts, si lowing how anxious bees are 
to save time; for instance, their habit of cutting 
holes and sucking the nectar at the bases of certain 
flowers, which they can, with a very little more trouble, 
enter by the mouth. Bearing such facts in mind, I can 
see no reason to doubt that an accidental deviation in 
the size and form of the body, or in the curvature and 
length of the proboscis, &c., far too slight to be appre¬ 
ciated by us, might profit a bee or other insect, so that 
an individual so characterised would be able to obtain 
its food more quickly, and so have a better chance of 
living and leaving descendants. Its descendants would 
probably inherit a tendency to a similar slight deviation 
of structure. The tubes of the corollas of the common 
red and incarnate clovers (Trifolium pratense and in- 
carnatum) do not on a hasty glance appear to differ in 
length; yet the hive-bee can easily suck the nectar out 
of the incarnate clover, but not out of the common red 
