Chap. XI. IN RELATION TO CROSS-FERTILISATION. 423 



we shall presently see that this holds good in their 

 felonious practice of biting holes through the corolla. 



It is a curious question how bees recognise the flowers 

 of the same species. That the coloured corolla is the 

 chief guide cannot be doubted. On a fine day, when 

 hive-bees were incessantly visiting the little blue flowers 

 of Lobelia erinus, I cut off all the petals of some, and 

 only the lower striped petals of others, and these flowers 

 were not once again sucked by the bees, although some 

 actually crawled over them. The removal of the two 

 little upper petals alone made no difference in their 

 visits. Mr. J. Anderson likewise states that when he re- 

 moved the corollas of the Calceolaria, bees never visited 

 the flowers.* On the other hand, in some large masses of 

 Geranium phseum which had escaped out of a garden, I 

 observed the unusual fact of the flowers continuing to 

 secrete an abundance of nectar after all the petals had 

 fallen off ; and the flowers in this state were still visited 

 by humble-bees. But the bees might have learnt that 

 these flowers with all their petals lost were still worth 

 visiting, by finding nectar id those with only one or 

 two lost. The colour alone of the corolla serves as 

 an approximate guide : thus I watched for some time 

 humble-bees which were visiting exclusively plants of 



* 4 Gardeners' Chronicle,' 1853, 

 p. 534. Kurr cut off the nectaries 

 from a large number of flowers of 

 several species, and found that 

 the greater number yielded seeds ; 

 but insects probably would not 

 perceive the loss of the nectary 

 until they had inserted their pro- 

 boscides into the holes thus 

 formed, and in doing so would 

 fertilise the flowers. He also re- 

 moved the whole corolla from a 

 considerable number of flowers, 

 and these likewise yielded seeds. 

 Flowers which are self- fertile 



would naturally produce seeds 

 under these circumstances ; but I 

 am greatly surprised that Delphi- 

 nium consolida, as well as an- 

 other species of Delphinium, and 

 Viola tricolor, should have pro- 

 duced a fair supply of seeds when 

 thus treated; but it does not ap- 

 pear that he compared the number 

 of the seeds thus produced with 

 those yielded by unmutilated 

 flowers left to the free access of 

 insects: 'Bedeutung der Nek* 

 tarien,' 1833, pp. 123-135. 



