108 ORIGIN OF SPECIES 



Let us now turn to the nectar-feeding insects; 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 insects depended in main part on its nectar for 

 food. I could give many facts showing 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 with 

 a very little more trouble, they can enter by the mouth. 

 Bearing such facts in mind, it may be believed that under cer- 

 tain circumstances individual differences in the curvature or 

 length of the proboscis, &c., too slight to be appreciated by 

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

 viduals 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 and incarnate clovers (Trifolium pratense and incar- 

 natum) do not on a hasty glance appear to differ in length; 

 yet the hive-bee can easily suck the nectar out of the incar- 

 nate 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 deter- 

 mines 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- 



