149 



ARTIFICIAL FERTILISATION AND CROSS- 

 BREEDING. 



PURE HYBRIDISATION, OR CROSSING DISTINCT SPECIES OF 

 PLANTS.* 



THE following are the rules I observe and the means which I 

 take to insure success in my experiments with reference to this 

 subject : 



i st. I long held it to be of vital importance to have the 

 separate plants intended for the parents in the cross, even 

 though both were hardy, put under glass, and I still recom- 

 mend it ; for, by doing so, you heighten the temperature an 

 important thing and you can better secure against the inter- 

 ference of winds and insects ; and though Darwin holds the 

 former of small account, I have reason for differing from him 

 there. But in the height of summer, pollen may be taken from 

 an outside plant to cross an inside one, and vice versa. If the 

 cross is to be made on an outside plant which cannot be con- 

 veniently removed, I cover it with a hand-glass or cloche. 



2d. I hold it not enough merely to emasculate the intend- 

 ed seed-bearing flower ; I take off every petal, for the petals 

 attract the insects, which seem guided more by their optics 

 than any sense of smell. This act of emasculation in some 

 cases I perform long before the expansion of the bloom ; for in 

 many plants e.g., in the Papilionaceae, some of the Rosaceae, 

 and Compositae self-fertilisation may, and does, often take 

 place in the unopened flower. This is not all. I sometimes 

 put a gauze bag over it ; if I do not, the mutilated bloom may 

 not escape that most troublesome of all insect pests, the 

 humble-bee, which in his unwieldy flight may come across it 



* By Isaac Anderson-Henry, Esq., F.L. S. A paper read before the 

 Botanical Society of Edinburgh, and since revised and augmented. Re- 

 printed by kind permission of the author. Interesting information on 

 artificial fecundation will be found in the ' Revue Horticole/ 1868, p. 

 376 ; 1869, pp. 136, 260, 335, and 346; 187^ p. 390. .>.: 



