9O HYBRIDISING AND CROSS-BREEDING. 



at present known. It is sufficient for us to know that the organs 

 of most plants are naturally adapted so as to secure fertility and 

 cross-fertilisation occasionally ; so that artificial cross-fertilisation 

 is but an attempt on our part to " mend nature, change it rather, 

 the art itself is nature." A very interesting paper on the subject 

 of cross-fertilisation by insect agency and natural self-fertilisation, 

 by Mr Meehan of Philadelphia, will be found in the * Gardeners' 

 Chronicle,' 1875, p. 327, 32 8. In tms paper he names a variety 

 of plants which are self-fertilising according to his experience, 

 and draws attention to the fact that the way in which plants 

 are fed influences their fertility to a much greater extent than 

 is generally supposed. According to Mr Meehan, the de- 

 gree of nourishment which plants obtain has a very wonder- 

 ful influence on their sexual organs : indeed his conclusion is 

 that female flowers are produced only in the best conditions 

 of vegetative vigour, while with a weakened vitality comes an 

 increased tendency to bear male flowers ; and when we con- 

 sider the occasional appearance of male and female flowers 

 simultaneously on such dioecious plants as Ccelebogyne, Hu- 

 mulus, Aucuba, many Palms, and Araucaria, this view seems 

 not only possible but also probable. From the facts given in the 

 paper above cited, Mr Meehan deduces the following state- 

 ments : 



i st. That the great bulk of coloured flowering- plants are 

 self-fertilisers. 



2d. That only to a limited extent do insects aid fer- 

 tilisation. 



3d. Self-fertilisers are every way as healthy and vigorous 

 as, and immensely more productive than, those dependent on 

 insect aid. 



4th. That where plants are so dependent, they are the worse 

 fitted to engage in the struggle for life, the great underlying 

 principle in natural selection. 



One great fact in reference to this fourth deduction should 

 not escape our notice viz., that all the plants which require 

 insect agency to enable them to produce seeds are singularly 

 deficient in economic value, so far as our knowledge now 

 extends. Fancy the millions of flowers produced by our cereal 

 crops requiring insect agency, and note how perfect is the 

 fertility of our corn plants, nearly every flower in a head of 

 wheat or barley becoming fertilised and developed with a pre- 

 cision and exactness that would be marvellous had we not 

 learned to regard the whole performance as a mere matter of 

 course. 



It is very singular to note the precocity of some seminal 



