2i6 PLANT-BREEDING 



on the old branches. x\fterward, the remaining fruiting 

 branches receive careful investigation. Their number 

 reaches many hundreds each year, the total sum of all his 

 hybrids amounting to some three hundred thousand, and 

 having afforded the selection material for nearly twenty 

 seasons. The comparison, of course, is based, in the first 

 place, on the inspection of those hybrids that are ripening 

 their fruit at the same time. But the best types of previous 

 years must be used as standards in the work, most of them 

 bearing fruit for a second or third time, and thus facilitating 

 the comparison. Finally some four or five are selected as 

 being ready for the trade, and these arc then multiplied as 

 rapidly as possible and offered for sale. 



The remainder, after the extirpation of all minor forms, 

 yields a harvest of hybrid seeds for the next sowing, and are 

 themselves destined for renewed crosses in the following 

 year. 



In his selections, Burbank is guided by a special gift of 

 judgment. By virtue of his long study of plums and by 

 the comparison of so many thousands of varieties of them, 

 he has acquired a rare and comprehensive knowledge of 

 all their qualities, which enables him to tell on his farm, 

 which kinds are the best for shipping, wliich for canning 

 purposes, which will be household fruits, and which good for 

 drying. He knows his trees, observes their behavior during 

 the winter, pays attention to the vigor of their growth and 

 the mode of their development, and from the inspection of 

 all these qualities, can distinguish the hardy varieties from 

 the unresistant ones, and predict for each the region and the 

 life conditions under whicn it will probably thrive. To a 

 large degree his choice is guided by such considerations, 

 and anyone who has a lesser experience in the selection of 

 prunes can hardly understand how it is at all possible to 

 choose the right kinds for their distinct uses, but the success 



