NATURAL SELECTION 75 



under certain circumstances individual differences in the curva- 

 ture or length of the proboscis, etc., too slight to be appreciated by 

 us, might profit a bee or other insect, so that certain individuals 

 would be able to obtain their food more quickly than others; and 

 thus the communities to which they belonged would flourish and 

 throw off many swarms inheriting the same peculiarities. The tubes 

 of the corolla of the common red or incarnate clovers (Trifolium 

 pra tense and incarnatum) 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 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. That this nectar is much liked by the hive-bee is certain; for 

 I have repeatedly seen, but only in the autumn, many hive-bees 

 sucking the flowers through holes bitten in the base of the tube by 

 humble-bees. The difference in the length of the corolla in the two 

 kinds of clover, which determines the visits of the hive-bee, must 

 be very trifling; for I have been assured that when red clover has 

 been mown, the flowers of the second crop are somewhat smaller, 

 and that these are visited by many hive-bees. I do not know 

 whether this statement is accurate; nor whether another published 

 statement can be trusted, namely, that the Ligurian bee, which is 

 generally considered a mere variety of the common hive-bee, and 

 which freely crosses with it, is able to reach and suck the nectar of 

 the red clover. Thus, in a country where this kind of clover 

 abounded, it might be a great advantage to the hive-bee to have a 

 slightly longer or differently constructed proboscis. On the other 

 hand, as the fertility of this clover absolutely depends on bees 

 visiting the flowers, if humble-bees were to become rare in any 

 country, it might be a great advantage to the plant to have a 

 shorter or more deeply divided corolla, so that the hive-bees should 

 be enabled to suck its flowers. Thus I can understand how a flower 

 and a bee might slowly become, either simultaneously or one after 

 the other, modified and adapted to each other in the most perfect 

 manner, by the continued preservation of all the individuals which 

 presented slight deviations of structure mutually favorable to each 

 other. 



I am well aware that this doctrine of natural selection, exem- 

 plified in the above imaginary instances, is open to the same ob- 

 jections which were first urged against Sir Charles Lyell's noble 

 views on "the modern changes of the earth, as illustrative of geol- 

 ogy;" but we now seldom hear the agencies which we see still at 

 work, spoken of as trifling or insignificant, when used in explaining 



