192 PLANT-BREEDING 



ing stoneless ones, each of which will be appropriate for the 

 the same culture and use as one of the older types. Here, 

 once more, the cjuestion arose, can the disappearance of the 

 stone be the result of the hybridization of two or more ordi- 

 nary varieties ? Burbank's answer was a negative. He had 

 followed c^uite another way in procuring this astonishing 

 result. He had noted that about two centuries ago, in 

 France, a prune bore the name of "Prune sans noyau." 

 It was an indifferent variety, more a curiosity than a 

 thing of commercial value, since it produced only small 

 fruit. But Burbank at once reahzed all the possibihties 

 which this stoneless form offered. He was quite convinced 

 that it needed only to be crossed with the best ordinary 

 kinds to give a new and most attractive fruit. He pro- 

 cured seed of this long-forgotten French prototype and sowed 

 them on his farm. By their first fruits he satisfied himself 

 of the correctness of the description of them, and of their 

 fitness for his work. Of course, by one crossing, the chance 

 is not large enough to get a desirable combination. Repeated 

 crossings are required, and each has to be accompanied by a 

 selection of the most promising specimens. In this way, 

 size, flavor, and fleshiness may steadily increase, while the 

 amount of the remnants of the stone is always kept as small 

 as possible. 



A counterpart to the stoneless prune, is the spineless 

 cactus. It belongs to the genus Opuntia, some species of 

 which are very celebrated, since they produce the Indian 

 figs, which may be seen in the markets of New York and 

 elsewhere in the eastern states, where, notwithstanding their 

 spines, they are highly appreciated as a dehcacy. The 

 Opuntias are desert plants, growing abundantly and in c^uite 

 a number of species on the plains of the semi-arid regions 

 of the West. Their stems consist of large flat pods, joined 

 together in the most fantastic manner. They are often seen 



