THE WHEAT PROBLEM AGAIN. 771 



supply the needs of 130,000,000 people on the basis of the imperfect 

 statistics and inadequate data of the past, becomes almost an imperti- 

 nence. It is much more probable that the 400,000 square miles which 

 now meet the needs of 75,000,000 people, with an enormous excess 

 for export, will in 1930 still suffice for the domestic supply of 

 130,000,000 people, with a proportionate export corresponding to the 

 present. 



If the product of the farms of the "West now yielding the largest 

 crops, or of the renovated lands of the South now yielding the best 

 crops, be taken as the average standard of the near future, as they 

 should be, then it may be true in 1930, as it is now, that one fifth of 

 the arable land of this country when put under the plow will still 

 suffice for all existing demands, the remainder of our great domain 

 extending the promise of future abundance and welfare to the yet 

 greater numbers who will occupy the land a century hence. 



I may add that in the course of a very friendly correspondence 

 with Sir William Crookes, while we are still at variance in our esti- 

 mates of the area which may be converted to the production of wheat 

 in this country without trenching upon any other product, we are 

 wholly at an agreement on a most material point. I quote from one 

 of his letters : " Under the present wasteful method of cultivation 

 there will be in a limited number of years an insufficient supply of 

 wheat. Apply artificial fertilizers judiciously, and the supply may 

 be increased indefinitely." I would only venture to add to the judg- 

 ment of so eminent a writer the words " or natural," to the end that 

 the paragraph should read, " Apply artificial or natural fertilizers 

 judiciously, and the supply can be increased. indefinitely." 



Many years ago I was asked among others, " What would be the 

 next great discovery of science or invention? ' ; To which I replied, 

 " A supply of nitrogen at low cost." Has not that discovery been 

 made in the recent development of the functions of the bacteria which, 

 living and dying upon the leguminous plants, dissociate the nitrogen 

 of the atmosphere and convert it through the plant to the renovation 

 of the soil ? Is not the invention of methods of nitrifying the soil by 

 distributing the germs of bacteria one of the most wonderful dis- 

 coveries of science ever yet attained? Can any one yet measure the 

 potential of any given area of land in any part of this country in the 

 production of any one of its great crops? That there is a limit may 

 be admitted. Can any one venture to say that any of our average 

 crops yet approach beyond a small fractional measure the true limit 

 of production, whatever it may be, either in cotton, maize, wheat, or 

 any other product of the soil ? 



In this, as in many other developments of the theory of evolution, 

 the factor of mental energy, which is the prime factor in all material 



