424 HABITS OF INSECTS CHAP. XL 



the white-flowered Spiranthes autumnalis, growing on 

 short turf at a considerable distance apart ; and these 

 bees often flew within a few inches of several other 

 plants with white flowers, and then without further ex- 

 amination passed onwards in search of the Spiranthes. 

 Again, many hive-bees which confined their visits to the 

 common ling (CaUuna vulgaris}, repeatedly flew towards 

 Erica tetralix, evidently attracted by the nearly similar 

 tint of their flowers, and then instantly passed on in 

 search of the Calluna. 



That the colour of the flower is not the sole guide, is 

 clearly shown by the six cases above given of bees 

 which repeatedly passed in a direct line from one 

 variety to another of the same species, although they 

 bore very differently coloured flowers. I observed also 

 bees flying in a straight line from one clump of a yellow- 

 flowered CEnothera to every other clump of the same 

 plant in the garden, without turning an inch from 

 their course to plants of Eschscholtzia and others with 

 yellow flowers which lay only a foot or two on either 

 side. In these cases the bees knew the position of each 

 plant in the garden perfectly well, as we may infer by 

 the directness of their flight ; so that they were guided 

 by experience and memory. But how did they discover 

 at first that the above varieties with differently coloured 

 flowers belonged to the same species ? Improbable as 

 it may appear, they seem, at least sometimes, to recog- 

 nise plants even from a distance by their general 

 aspect, in the same manner as we should do. On three 

 occasions I observed humble-bees flying in a perfectly 

 straight line from a tall larkspur (Delphinium) which 

 was in full flowei to another plant of the same species 

 dt the distance of fifteen yards which had not as yet a 

 single flower open, and on which the buds showed only 

 a faint tinge of blue. Here neither odour nor the 



