Ohap. IV.] NATL HAL SELECTION. 117 



vature or length of the proboscis, &e., 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 communi- 

 ties to which they belonged would flourish and throw ofE 

 many swarms inheriting the same peculiarities. The 

 tubes of the corolla of the common red and incarnate 

 clovers (Trifolium 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 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 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 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 



