III. 



« 



The Cross-Fertilisation of Food-Plants. 



SUCH a Society as the Royal Agricultural, which boasts the motto, 

 " Practice with Science," could not better carry out its principles 

 than by encouraging experiments in the cross-fertilisation of food- 

 plants. Darwin, we know, put forward conclusive evidence in favour 

 of cross-fertilisation as a general rule for the production of the 

 strongest and most fertile offspring, and insisted on the advantage or 

 necessity in all cases of an occasional cross. These are points which 

 scientists universally accept ; yet so great is the gulf still between 

 practice and science, that the vegetative method is to-day often the 

 only one used in the propagation of our most necessary crops ; i.e., 

 this year's plants are produced, not from the seed, but from cuttings 

 or some detached portion of last year's plants. 



The potato plant, for instance, has been taken from a light soil 

 in the cool, dry, even climate of the mountains of Chili and grown for 

 years in all soils in the warm, damp, changeable climate of the 

 British Isles, and, to make matters worse, instead of starting again 

 and again with new individuals produced from seed, the life of single 

 individuals has been indefinitely protracted by purely vegetative 

 reproduction. Part of an older plant, namely the tuber, has been 

 divided up into new plants, and this process has been repeated till, 

 under the artificial conditions of growth and multiplication, the plant 

 has lost all stamina. What wonder, then, that the last fifty years tells 

 a tale of continued struggle between the weakened plant and disease? 

 It is to cross-fertilisation that we are now looking for help in the 

 fight with the fungoid and other pests which have done, and are 

 doing, so much damage. During the last few years Messrs. Sutton 

 have raised seedlings by crossing a variety of the common potato, 

 Solanum tuberosum, with another species, Solamim Maglia, or, as it is 

 sometimes called, Darwin's potato ; and, though it is too early for 

 definite statement, we may hope that in a few years some of the 

 seedlings will prove the precursors of varieties yielding crops good in 

 themselves and also less liable to disease. Not only is there the 

 strengthening influence of the new blood introduced by the cross, but 

 the advantageous fact that Solanum Maglia is a native of a damper, 

 warmer climate, more like our own than is that to which the common 

 potato is indigenous. 



