Next to the United States Russia is the greatest wheat exporter, but the Russian peasant population increases more rapidly than any other in Europe, even though it is inadequately fed, and this source of supply must fail ere very long. As Sir William points out, the Caucasian civilisation is indeed founded upon bread. “Other races vastly superior to us in numbers, but differing widely in material and intellectual progress, are eaters of Indian corn, rice, millet and other grains; but none of these grains have the food-value, concentrated health-sustaining power of wheat.” Sir William's argument was, and is, that we must learn how to fix the nitrogen of the atmosphere--that is to say, how to combine it in forms on which the plant can feed. “The fixation of nitrogen is a question of the not far distant future. Unless we can class it among certainties to come, the great Caucasian race will cease to be foremost in the world, and will be squeezed out of existence by races to whom wheat and bread is not the staff of life.” Sir William Crookes was himself the pioneer in the discovery of the electric method of fixing the atmospheric nitrogen, and now, a decade after the delivery of his address, this method is in successful commercial employment in Scandinavia. There is also a method of sowing the bacteria which are capable of fixing nitrogen and this, according to some, has been already proved practicable. Further, the Mendelians offer us the possibility of new varieties of wheat having more grains to the stalk than we obtain at present. By these methods the output of the land devoted to wheat may be doubled or trebled, but it is evident that even then there will be an impassable limit. We have to face, indeed, the evident but unconsidered fact that _there must be a maximum possible human population for this finite earth_, whether a bread-eating population or any other. I do not propose to speculate regarding this evident truth. If human life is worth living and is the highest life we know, we may desire to obtain that maximum population, but it must be obtained, and its limits observed, by the humane and decent processes which man is capable of putting into practice, and not by the check of starvation.