88 ILLVSTRATI0N8 Off TUB ACTION 



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 certain circumstances individual differences in 

 the curvature or length of the probocis, 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 (Trifo- 

 lium pratense 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 abun- 

 dant 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 com- 

 mon 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 difierently constructed proboscis. On the other hand, 

 as the fertility of this clover absolutely depends on bees vis- 

 iting the flowers, if humble-bees were to become raref in any 



