Another of Mr. Burbank’s achievements is the evergreen crimson rhubarb, which is not only far less acid than the old variety, but richer in flavor and a giant in size. The pomato, a tomato grown on a potato plant, is most interesting. The plant is a free bearer, having a white, succulent, delicious fruit, admirable when cooked, used in a salad, or eaten fresh as our other fruit. The experiments with prunes conducted at the Santa Rosa ranch have been of the greatest value to the state. For forty years the prune growers of the Pacific slope had been searching for a variety of this fruit which would be as rich in sugar and as abundant a bearer as the little California prune of commerce, and yet of a larger size, and earlier in its time of ripening. Mr. Burbank with his famous sugar prune filled all these requirements, and revolutionized the prune industry of the state. Besides this triumph he has succeeded in obtaining a variety of this fruit having a shell-less kernel, so that the fruit when dried much resembles those which are artificially stuffed. The flowers which Mr. Burbank has evolved by his methods, and those which he has simply enlarged and glorified, are far too numerous to be named here. In 1905 a grant of ten thousand dollars a year was bestowed upon Mr. Burbank by the Carnegie Institution of Washington, D.C., for the purpose of assisting him in his experiments. Seldom has money been better placed. Chapter XVI The Hidden Treasures of Mother Earth Thousands of years ago, before the time of which we have any history, there were rivers in California,--rivers now dead,--whose sides were steeper and whose channels were wider than those of the rivers in the same part of the world to-day. Rapid streams they were, and busy, too; washing away from the rocks along their sides the gold held there, dropping the yellow grains down into the gravelly beds below. After a time there came down upon these rivers a volcanic outflow; great quantities of ashes, streams of lava and cement, burying them hundreds of feet deep, until over them mountain ridges extended for miles and miles. Other changes in the earth’s surface took place, and in the course of time our streams of to-day were formed. As they cut their way through the mountain ranges, some of them crossed the channels of old dead rivers, and finding the gold hidden there, carried some of it along, rolling it over and over, mixed with sand and gravel, down into the lower lands under the bright sunlight. Here it was found by Marshall and the gold hunters who followed him. These were the placer mines of which we read in Chapter VII.