226 PLANT-BREEDING 



and in the thin shell of its seed. As a variety it has been 

 given the name of white walnut. Its nuts are white and do 

 not need the artificial bleaching of the other sorts to which 

 the tannin of the coats gives their dark appearance. The 

 pit on the inside of the nut is of a pure white and sweet, 

 because the astringent taste of the shell and the meat has been 

 taken away from it. This variety was started from some 

 of his hybrid nuts which, at first, gave some indication and 

 promise of success in this line of improvement. 



In contrast to these pure sports I now mention the cases 

 / in which a combination, obtained by means of a cross, is 

 so strikingly different from what could be expected that it is 

 instantly designated a "sport." The Bartlett plum is such 

 a chance seedling among the plum hybrids of the Sebastopol 

 farm. We inspected the tree, but the fruit was not yet 

 ripe. It is quite different from other plums. It branched 

 from its very base and had erect shoots with a fine peculiar 

 foliage. Its plums have the taste and fragrance of a Bartlett 

 pear, and even the meat resembles that of this well-known 

 fruit. Visitors whom Burbank requested to eat it with 

 their eyes shut, have taken it for a pear. It sprang up in a 

 lot of hybrid seedlings, most of which had been produced 

 by crossing the Kelsey and the Simoni, but for this individ- 

 ual seedling the ancestry could not be traced. It is, how- 

 ever, an evident combination, and all of its qualities can be 

 traced to its probable parents, the flavor being mainly due 

 to the Prunus Simoni. 



The stoneless prunes and the spineless edible cacti 

 are such evident hybrids that it is doubtful whether anybody 

 would designate them as sports. I have already given a 

 general description of them, but shall now add some details. 

 About the year 1887, Burbank received his first "prune sans 

 noyau" from a French nurseryman. It soon fruited and 

 produced a fruit about the size of a small cherry. It was 



