386 CKOSS-FERTILISATION. CHAP. X 



does not depend altogether on their inconspicuousness, 

 but likewise on the absence of some sufficient attraction ; 

 for the flowers of Trifolium arvense are extremely 

 small, yet are incessantly visited by hive and humble- 

 bees, as are the small and dingy flowers of the 

 asparagus. The flowers of Linaria cymbalaria are 

 small and not very conspicuous, yet at the proper time 

 they are freely visited by hive-bees. I may add that, 

 according to Mr. Bennett,* there is another and quite 

 distinct class of plants which cannot be much frequented 

 by insects, as they flower either exclusively or often 

 during the winter, and these seem adapted for self- 

 fertilisation, as they shed their pollen before the flowers 

 expand. 



That many flowers have been rendered conspicuous 

 for the sake of guiding insects to them is highly 

 probable or almost certain ; but it may be asked, have 

 other flowers been rendered inconspicuous so that they 

 may not be frequently visited, or have they merely 

 retained a former and primitive condition ? If a plant 

 were much reduced in size, so probably would be the 

 flowers through correlated growth, and this may possibly 

 account for some cases ; but the corolla, as I have else- 

 where shown (' Different Forms of Flowers,' 1877, p. 

 143), is also liable to be greatly reduced, through the 

 direct action of unfavourable climate. Size and colour 

 are both exiremely variable characters, and it can 

 hardly be doubted that if large and brightly-coloured 

 flowers were advantageous to any species, these could be 

 acquired through natural selection within a moderate 

 lapse of time. Papilionaceous flowers are manifestly 

 constructed in relation to the visits of insects, and it 

 seems improbable, from the usual character of the 



* ' Nature,' 1869, p. 11. 



