Chap. XI. IN RELATION TO CROSS-FERTILISATION. 427 



fond of sugar and of any sweet fluid, and as they do 

 not disdain the minute drops on the glands of Prunus 

 laurocerasus, it is a strange fact that they do not suck 

 the nectar of many open flowers, which they could do 

 without the aid of a proboscis. Hive-bees visit the 

 flowers of the Symphoricarpus and Tritoma, and this 

 makes it all the stranger that they do not visit the 

 flowers of the Epipactis, or, as far as I have seen, those 

 of the Scrophularia aquatiea; although they do visit 

 the flowers of Scrophularia nodosa, at least in North 

 America.* 



The extraordinary industry of bees and the number 

 of flowers which they visit within a short time, so that 

 each flower is visited repeatedly, must greatly increase 

 the chance of each receiving pollen from a distinct 

 plant. When the nectar is in any way hidden, bees 

 cannot tell without inserting their proboscides whether 

 it has lately been exhausted by other bees, and 

 this, as remarked in a former chapter, forces them to 

 visit many . more flowers than they otherwise would. 

 But they endeavour to lose as little time as they can; 

 thus in flowers having several nectaries, if they find 

 one dry they do not try the others, but as I have often 

 observed, pass on to another flower. They work so in- 

 dustriously and effectually, that even in the case of 

 social plants, of which hundreds of thousands grow 

 together, as with the several kinds of heath, every 

 single flower is visited, of which evidence will presently 

 be given. They lose no time and fly very quickly 

 from plant to plant, but I do not know the rate at 

 which hive-bees fly. Humble-bees fly at the rate of 

 ten miles an hour, as I was able to ascertain in the case 

 of the males from their curious habit of calling at 



Silliman's American Journal of Science,' Aug. 1871. 



