COLOURS OF FLOWERS. 183 



not always : several experimenters assert that, after every 

 precaution, the offspring exactly resemble the maternal 

 parent. But one rule florists always adopt in order to 

 enhance the colouring is to use the pollen of the better- 

 coloured plant, the maternal parent being usually the in- 

 ferior one. 



As an illustration of the relative effect, of crossing and 

 self-fertilisation respectively on the production of colours, 

 I quote the following passage from Mr. Darwin's work : * 

 " The flowers produced by self-fertilised plants of the fourth 

 generation [of Dianthus caryopliyllus or Carnation] were as 

 uniform in tint as those of a wild species, being of a pale 

 pink or rose-colour. Analogous cases [occurred] with 

 Mimulus and Ipomoea. . . . On the other hand, the flowers 

 of plants raised from a cross with the fresh stock which bore 

 dark crimson flowers, varied extremely in colour. . . . The 

 great majority had their petals longitudinally and variously 

 striped with two colours." 



Uniformity and paleness of tint are thus correlated Avith 

 self-fertilisation; and since, whenever the latter process is 

 persevered with, an increase of fertility follows, it is not 

 surprising to find that such tints are usually accompanied 

 by an increased power of seed-bearing. Thus, Mr. Darwin 

 found that, "the proportional number of seeds per capsule 

 produced by the plants [of Dianthus'] of crossed origin, to 

 those by the plants of self -fertilised origin, was as 100 : 125." 

 Again, of Antirrliinum majtis, the relative self-fertility of red 

 and white varieties was as 98 : 20 ; of Mimulus luteus the 

 same comparison gave the ratio of 100 : 147; while pale- 

 coloured Pelargoniums are notoriously great seeders. "f 



* Cross and Self Fertilisation, etc., p. 139. 



f For further illustrations, see mj paper on Self.fertilisation, etc. 



