Page:Popular Science Monthly Volume 67.djvu/348

348 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 qualities 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 $$\times$$ triflora, and then Americana $$\times$$ 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 results. Burbank endeavored to combine the plum and the apricot and succeeded in getting a new fruit, which he calls plumcot, of very delicious 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 instance 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-colored 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 variegated 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