HYBRIDISING AND CROSS-BREEDING. 89 



as clearly as possible how plants may be artifically fertilised 

 so as to change and if possible improve them, either in 

 use or beauty. Cross-fertilisation seems in many cases to in- 

 fuse fresh life or additional vegetative vigour into cultivated 

 seedling plants, besides changing them materially in habit and 

 colour of flower, or in the size and flavour of their seeds or 

 fruits. 



Increased Vigour. I have in several cases noted the healthy 

 vigorous appearance of Mr Dominy's hybrid and bigeneric hy- 

 brid Orchids compared with the parent plants, and Cypripedium 

 Harrissianum (C. barbato-villosuni) or Calanthe Veitchii may 

 be cited as examples, being more robust than either of their 

 parents, and more profuse bloomers; but in some cases we find 

 that this vigour is at the expense of fertility in the hybrid, hence 

 they are called mules. In the animal kingdom, also, this 

 hardy vigour seems transmitted to sterile hybrids, the mule 

 being capable of more prolonged exertion than either the horse 

 or the ass. But while the occasional infusion of fresh blood 

 by cross -fertilisation is beneficial 'and invigorating to either 

 animals or plants, cross-breeding in-and-in very often pro- 

 duces weakly and debilitated progeny. Some few hybrids or 

 mules between distinct species are sterile or barren in the 

 first generation, while on the other hand crosses between two 

 forms of the same species are not unfrequently more vigorous 

 and prolific than their parents in growth, flower, and fruit 

 while under cultivation ; but it will be found that they possess 

 far less " staying " power, and either revert to the normal type 

 or die out, if they have to compete with other vegetables in 

 the universal struggle for existence. It is curious to observe 

 that varieties in some cases cannot be crossed ; while some 

 plants, like Tacsonia, are more readily fertilised by the pollen 

 of other species than by that from their own flowers. Hybrids 

 also vary from complete or even increased fertility to entire 

 sterility. I particularly wish to point out that all our improve- 

 ments, however valuable they may be in a state of cultivation, 

 either for use or ornament, are actually inferior to their wild 

 parents when relegated to a state of nature ; and this is a most 

 important fact, and one which proves the unyielding pressure of 

 that curse which the first gardener incurred in the first garden. 



Natural Cross-fertilisation. We need not here look into the 

 mysteries of irritable or dimorphic stamens, elastic glutinous 

 caudicles, and the many other simple or intricate arrangements 

 by which nature secures that occasional cross so essential to pro- 

 longed fertility and vigorous heatlh, since the works of Darwin, 

 Lubbock, and others explain all these devices fully, so far as is 



