CHAP. XL PERFORATION OF THE COROLLA. 437 



had many flowers perforated ; but I found three plants 

 in separate parts of the garden which had sprung up 

 accidentally, and these had not a single flower per- 

 forated. General Strachey formerly saw many per- 

 forated flowers in a garden in the Himalaya, and he 

 wrote to the owner to inquire whether this relation 

 between the plants growing crowded and their per- 

 foration by the bees there held good, and was answered 

 in the affirmative. Mr. Bailey informs me that the 

 Gerardia pedicularia which is so largely perforated, 

 and Impatiens fulva, are both profuse flowerers. Hence 

 it follows that the red clover (Trifolium pratense) and 

 the common bean when cultivated in great masses in 

 fields, that Erica tetrcdix growing in large numbers 

 on heaths, rows of the scarlet kidney-bean in the 

 kitchen-garden, and masses of any species in the 

 flower-garden, are all eminently liable to be per- 

 forated. 



The explanation of this fact is not difficult. Flowers 

 growing in large numbers afford a rich booty to the 

 bees, and are conspicuous from a distance. They are 

 consequently visited by crowds of these insects, and I 

 once counted between twenty and thirty bees flying 

 about a bed of Pentstemon. They are thus stimulated 

 to work quickly by rivalry, and, what is much more 

 important, they find a large proportion of the flowers, 

 as suggested by my son,* with their nectaries sucked 

 dry. They thus waste much time in searching many 

 empty flowers, and are led to bite the holes, so as 

 to find out as quickly as possible whether there is any 

 nectar present, and if so, to obtain it. 



Flowers which are partially or wholly sterile unless 

 visited by insects in the proper manner, sucb as 



* ' Nature,' Jan. 8, 1874, p. 189. 



