342 POPULAR SCIENCE MONTHLY. 



as large numbers as possible, so that among the numberless undesirable 

 and imperfect plants we may choose the best. The chances are that 

 from the five or six desired good characters only three or four are 

 found together. Thousands of seedlings have to be developed in order 

 to create a possibility of finding one form in which the expected quali- 

 ties are present. It is a game of solitaire on a large scale. I may 

 mention as an example of this the production of the Alhambra plum, 

 which was obtained by combining European, American and Japanese 

 kinds. It took thirteen years to combine all these. First came the 

 crossing of the Kelsey with the Prunus Pissardi. Their hybrid was 

 crossed with French prunes. In the meantime various other crossings 

 were created, and it was made possible to work the pollen of these ' into 

 the strain/ as the term is called. First came Simoni X triflora, and 

 then Americana X nigra. This sevenfold combination gave us the 

 variety now known in the market as the Alhambra. 



We can go still further and cross species that are yet more widely 

 separated. It is then naturally even more difficult to predict the re- 

 sults. Burbank endeavored to combine the plum and the apricot and 

 succeeded in getting a new fruit, which he calls plumcot, of very deli- 

 cious taste and looking very much like an apricot, but combining the 

 soft skin of this fruit with the dark color of the plum. Burbank had 

 a number of varieties of this new fruit, some with a yellow fruit-flesh, 

 others of dark red color, light rose or white. In taste these plumcots 

 differ considerably. 



Burbank is equally successful in hybridizing flowers. In the in- 

 stance of the Callas — well known through the many varieties of 

 Richardia aethiopica — all the new cultivated forms have been hybrids 

 of a few species. Burbank, however, crossed Calla hastata, the yellow 

 ' Pride of Congo/ C. Elliottiana with dark yellow flowers and spotted 

 leaves, C. Pentlandi, also yellow with dark purple spots, the rose-col- 

 ored C. Rehmanni, and the small light yellow C. Nelsoni. From all 

 these he received a great number of different hybrids, among which 

 were found the most varying shades of color, very large-sized as well 

 as dwarfish forms. The colors were not limited to spadix and spathe, 

 but spread over peduncles and petioles, and even the leaves were varie- 

 gated with spots and stripes. In addition to these peculiar colors and 

 forms the hybrid Callas, of which Burbank had long rows in bloom at 

 the time of our visit, possess a hardiness and adaptability to extreme 

 temperatures, which fit them for outdoor cultivation, where formerly 

 Callas could be forced to full development only in hothouses. Every 

 year these hybrids are again subjected to the process of crossing, and 

 each year new and often unexpected forms appear. How far this will 

 go it is at present impossible to predict. 



Because of the favorable climatic conditions under which Burbank 



