Chap. IV. 
NATURAL SELECTION. 
95 
clover, which is visited by humble-bees alone; so that 
whole fields of the red clover offer in vain an abundant 
supply of precious nectar to the hive-bee. Thus it 
might be a great advantage to the hive-bee to have a 
slightly longer or differently constructed proboscis. On 
the other hand, I have found by experiment that the 
fertility of clover depends on bees visiting and moving- 
parts of the corolla, so as to push the pollen on to the 
stigmatic surface. Hence, again, if humble-bees were 
to become rare in any country, it might be a great 
advantage to the red clover to have a shorter or more 
deeply divided tube to its corolla, so that the hive-bee 
could visit its flowers. Thus I can understand how a 
flower and a bee might slowly become, either simul¬ 
taneously or one after the other, modified and adapted 
in the most perfect manner to each other, by the con¬ 
tinued preservation of individuals presenting mutual 
and slightly favourable deviations of structure. 
I am well aware that this doctrine of natural selection, 
exemplified in the above imaginary instances, is open to 
the same objections which were at first urged against 
Sir Charles Lyell’s noble views on the modern changes 
of the earth, as illustrative of geology;” but.we now 
seldom hear the action, for instance, of the coast-waves, 
called a trifling and insignificant cause, when applied 
to the excavation of gigantic valleys or to the formation 
of the longest lines of inland cliffs. Natural selection 
can act only by the preservation and accumulation 
of infinitesimally small inherited modifications, each 
profitable to the preserved being; and as modern 
geology has almost banished such views as the excava¬ 
tion of a great valley by a single diluvial wave, so 
will natural selection, if it be a true principle, banish 
the belief of the continued creation of new organi(3 
