Cross- Breeding and Hybridizing , 15 



of some garden crops, in which many seeds are produced in each fruit and in 

 which the operation of pollination is easy, actual hand-crossing from new 

 stock now and then may be found to be profitable. But in most cases, the 

 operation can be left to nature, if the new stock is planted among the old. 

 Upon this point Darwin expressed himself as follows: "It is a common 

 practice with horticulturists to obtain seeds from another place having a very 

 different soil, so as to avoid raising plants for a long succession of genera- 

 tions under the same conditions ; but with all the species which freely inter- 

 cross by the aid of insects or the wind, it would be an incomparably better 

 plan to obtain seeds of the required- variety, which had been raised for some 

 generations under as different conditions as possible, and sow them in alter- 

 nate rows with seeds matured in the old garden. The two stocks would then 

 intercross, with a thorough blending of their whole organization, and with 

 no loss of purity to the variety ; and this would yield far more favorable re- 

 sults than a mere change of seeds." 



But you are waiting for a discussion of the second of the great features of 

 crossing — the summary production of new varieties. This is the subject 

 which is almost universally associated with crossing in the popular mind, 

 and even among horticulturists themselves. It is the commonest notion that 

 the desirable characters of given parents can be definitely combined in a 

 pronounced cross or hybrid. There are two or three philosophical reasons 

 which somewhat oppose this doctrine and which we will do well to consider 

 at the outset. In the first place, nature is opposed to hybrids, for species 

 have been bred away from each other in the ability to cross. If, therefore, 

 there is no advantage for nature to hybridize, we may suppose that there 

 would be little advantage for man to do so ; and there would be no advantage 

 for man.did he not grow the plant under conditions different from nature or 

 desire a different set of characters. We have seen that nature's chief bar- 

 riers to hybridization are total refusal of species to unite, and entire or com- 

 parative seediessness of offspring. We can overcome the refusal to cross in 

 many cases by bringing the plant under cultivation ; for the character of the 

 species becomes so changed by the wholly new conditions that its former 

 antipathies may be overpowered. Yet it is doubtful if such a plant will ever 

 acquire a complete willingness to cross. In like manner we can overcome 

 in a measure the comparative seediessness of hybrids, but it is very doubt- 

 ful if we can ever make such hybrids completely fruitful. It would appear, 

 therefore, upon theoretical grounds, that in plants in which fruits or seeds are 

 the parts sought, no good can be expected, as a rule, from hybridization, and 

 this seems to be affirmed by facts. 



It is evident that species which have been differentiated or bred away from 

 each other in a given locality will have more opposed qualities or powers than 



