A^D INSECT AID. 227 



of the style. In some cases the style is absent and the stigma is 

 consequently sessile." For our present purpose the stamen may 

 be regarded as the fertilising organ, and the pistil as the seed- 

 bearing organ. In an ordinary flower the pistil is surrounded by 

 a row of stamens, and at first sight it would appear that a more 

 simple arrangement for the reproduction of the plant could not 

 well be contrived. The pollen would seem to be arranged to fall 

 upon and dust the stigma of the pistil, and effect what is known as 

 close fertilisation. This does happen with some flowers, chiefly 

 with the inconspicuous ones. In the largest number of flowers 

 with a gay corolla, or which emit a sweet scent and possess honey- 

 glands, cross-fertilisation is the rule and close fertilisation the 

 exception. 



There are various contrivances in these flowers which effect- 

 ually prevent self-fertilisation. In many species the stamens and 

 pistils are situated in different flowers. Such species are named 

 diclinous ; when the stamens and pistils are situated in different 

 flowers on the same plant, the species is called monoecious ; when 

 on different i)lants dioecious. Delpino has classified flowers into 

 Anemophilous (literally wind-lovers) and Entomophilous (insect- 

 lovers), denoting wind-fertilised and insect-fertilised. It is not my 

 purpose in this paper to treat of the former, but will observe that 

 wind-fertilised flowers are mostly neutral or dull in colour, destitute 

 of odour and honeyless. Pines, firs, and other Conifene are 

 examples of anemophilous plants. Dr. Asa Gray observes that 

 " Insect fertilisable or entomophilous flowers are correlated with 

 showy colouration (including white, which is most showy at dusk), 

 odour or secretion of nectar, often by all three modes of attraction 

 to insects combined. Some insects, moreover, visit flowers for 

 their pollen, a highly nutritious article, and ordinarily produced in 

 such abundance that much may be spared. The showiness of the 

 corolla or other floral envelopes is an attractive adaptation to 

 fertilisation, enabling blossoms to be discerned at a distance; nor 

 do we know that fragrance or other scent, or that nectar, subserves 

 any other uses to the flower than that of alluring insects." 



Adaptations in the pollen of such blossoms for transportation 

 by insects are various. Commonly the grains are slightly moist or 

 glutinous, or roughish, or studded with projection, or strung with 



