These are undoubtedly extraordinary crops, but quite recently the French Professor Aimé Girard undertook a series of experiments in order to find out the best conditions for growing potatoes in his country.[79] He did not care for show-crops obtained by means of extravagant manuring, but carefully studied all conditions: the best variety, the depth of tilling and planting, the distance between the plants. Then he entered into correspondence with some 350 growers in different parts of France, advised them by letters, and finally induced them to experiment. Strictly following his instructions, several of his correspondents made experiments on a small scale, and they obtained--instead of the three tons which they were accustomed to grow--such crops as would correspond to twenty and thirty-six tons to the acre. Moreover, ninety growers experimented on fields more than one-quarter of an acre in size, and more than twenty growers made their experiments on larger areas of from three to twenty-eight acres. The result was that _none of them obtained less than twelve tons_ to the acre, while some obtained twenty tons, and the average was, for the 110 growers, fourteen and a half tons per acre. However, industry requires still heavier crops. Potatoes are largely used in Germany and Belgium for distilleries; consequently, the distillery owners try to obtain the greatest possible amounts of starch from the acre. Extensive experiments have lately been made for that purpose in Germany, and the crops were: Nine tons per acre for the poor sorts, fourteen tons for the better ones, and thirty-two and four-tenths tons for the best varieties of potatoes. Three tons to the acre and more than thirty tons to the acre are thus the ascertained limits; and one necessarily asks oneself: Which of the two requires _less labour_ in tilling, planting, cultivating and digging, and less expenditure in manure--thirty tons grown on ten acres, or the same thirty tons grown on one acre or two? If labour is of no consideration, while every penny spent in seeds and manure is of great importance, as is unhappily very often the case with the peasant--he will perforce choose the first method. But is it the most economic? * * * * *