A number of investigators have attempted to determine the weight of the roots as compared with the weight of the plant above ground, hut the subject, because of its great experimental difficulties, has not been very accurately explained. Schumacher, experimenting about 1867, found that the roots of a well-established field of clover weighed as much as the total weight of the stems and leaves of the year's crop, and that the weight of roots of an oat crop was 43 per cent of the total weight of seed and straw. Nobbe, a few years later, found in one of his experiments that the roots of timothy weighed 31 per cent of the weight of the hay. Hosaeus, investigating the same subject about the same time, found that the weight of roots of one of the brome grasses was as great as the weight of the part above ground; of serradella, 77 per cent; of flax, 34 per cent; of oats, 14 per cent; of barley, 13 per cent, and of peas, 9 per cent. Sanborn, working at the Utah Station in 1893, found results very much the same Although these results are not concordant, they show that the weight of the roots is considerable, in many cases far beyond the belief of those who have given the subject little or no attention. It may be noted that on the basis of the figures above obtained, it is very probable that the roots in one acre of an average wheat crop would weigh in the neighborhood of a thousand pounds--possibly considerably more. It should be remembered that the investigations which yielded the preceding results were all conducted in humid climates and at a time when the methods for the study of the root systems were poorly developed. The data obtained, therefore, represent, in all probability, minimum results which would be materially increased should the work be repeated now. The relative weights of the roots and the stems and the leaves do not alone show the large quantity of roots; the total lengths of the roots are even more striking. The German investigator, Nobbe, in a laborious experiment conducted about 1867, added the lengths of all the fine roots from each of various plants. He found that the total length of roots, that is, the sum of the lengths of all the roots, of one wheat plant was about 268 feet, and that the total length of the roots of one plant of rye was about 385 feet. King, of Wisconsin, estimates that in one of his experiments, one corn plant produced in the upper 3 feet of soil 1452 feet of roots. These surprisingly large numbers indicate with emphasis the thoroughness with which the roots invade the soil. Depth of root penetration