Darwin's Artificial and Natural Selection 125 
ing and surviving. The plants which produced flowers with 
the largest glands or nectaries, excreting most nectar, would 
oftenest be visited by insects, and would oftenest be crossed ; 
and so in the long run would gain the upper hand and form 
a local variety.” 
The reader will notice that the sweet juice or nectar 
secreted by certain plants is supposed to have first appeared 
independently of the action of natural selection. Why then 
account for its presence in flowers as the outcome of an 
entirely different process? If the nectar is eagerly sought 
for by insects, without the plant benefiting in any way by 
their visitations, why give a different explanation of its origin 
in flowers where it is of benefit to the plant ? 
Darwin carries his illustration further: “When our plant, 
‘by the above process long continued, had been rendered 
highly attractive to insects, they would unintentionally, on 
their part, regularly carry pollen from flower to flower; and 
that they do this effectually, I could easily show by many 
striking facts. I will give only one, as likewise illustrating one 
step in the separation of the sexes of plants.... As soon 
as the plant had been rendered so highly attractive to insects 
that pollen was regularly carried from flower to flower, another 
process might commence. No naturalist doubts the advan- 
tage of what has been called the ‘ physiological division of 
labour’; hence we may believe that it would be advantageous 
to a plant to produce stamens alone in one flower or on one 
whole plant, and pistils alone in another flower or on another 
plant. In plants under culture and placed under new con- 
ditions of life, sometimes 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 
