were still laborious, but sure; M. Boussingault employed them, and in a few years succeeded in, to a large extent, sketching the great work which is still being prosecuted, without in any way changing the programme which the masters had laid out nearly fifty years before. His robust good sense was not deceived. He saw how the problem could be approached with exact methods of elementary analysis. If he had tried at this time to follow in M. Chevreul's tracks and undertake the immediate analysis of agricultural products, he would have been foiled. The time had not come, and it is interesting to compare from this point of view his first experiments on germination with those which he executed forty years later, when the progress of organic chemistry had made accessible what was not within reach at the beginning." In his analysis of plant-foods and his studies of the origin of the nitrogen in herbivorous animals, the rigor of his methods was marked; his conclusions were reached slowly, not from one or a few experiments, but after a series of them. "One must know," he would say, "how to criticise himself; it is not till after he has exhausted all objections that he can estimate the value of them, and come to a conclusion." His labors were characterized rather by the clear and precise view of the end to be reached, abundance of observed facts, and lucidity of demonstration, than by ingenuity of methods. It was only rarely that he permitted himself to indulge in those bold and specious generalizations which are so pleasing to many and are so quickly forgotten; and before the end of his life he was cured of all disposition toward them. "Skepticism, even a little harsh in regard to the labors of others, had become habitual with him."
With such slow deliberation and painstaking care he pursued through more than thirty years, in his laboratory and upon his farm at Bechelbronn, his experiments on the composition of plants and their parts; of soils and manures; the effects of different soils and different manures, of no soil (or only sand or gravel) and no manure, of air as it exists and of air purified of all foreign elements, upon the growth of plants; varying the experiments in every conceivable way, year after year, testing them one by another, and comparing them one with another—all for the double purposes of learning whence plants derive their nitrogen, and what are the best kind and form of fertilizing material for each plant and for each kind and condition of soil. The first question is still not solved. On the other side, the investigations have contributed greatly to the improvement of agricultural methods and to the rewards of wise cultivation. The results of these studies are embodied in the "Rural Economy" and the "Agronomy," and in such papers in the journals of scientific societies as those on "The Estimation of Ammonia in Waters"; on "The Quantity of Am-
