556 ANNUAL BEPOET SMITHSONIAN INSTITUTION, 1913. 



But signs are not wanting that increase in this way will not go on 

 indefinite] 3^ We note (also from Dr. Unstead's paper) that in the 

 two later periods the percentage of total wheat produced which was 

 exported from the United States fell from 32 to 19, the yield per acre 

 showing an increase meanwhile to 14 bushels. In the Eussian Empire 

 the percentage fell from 26 to 23, and only in the youngest of the new 

 countries — Canada, Australia, and the Argentine — do we find large 

 proportional increases. Again, it is significant that in the United 

 Kingdom, which is, and always has been, the most sensitive of all 

 wheat-producing countries to variations in the floating supply, the 

 rate of falling off of home production shows marked if irregular 

 diminution. 



Looking at it in another way, we find (still from Dr. Unstead's 

 figures) that the total amount sent out by the great exporting coun- 

 tries averaged in 1881-1890, 295,000,000 bushels; 1891-1900, 402,- 

 000,000; 1901-1910, 532,000,000. These quantities represent, respec- 

 tively, 13, 15.6, and 16.1 per cent of the total production, and it 

 would appear that the percentage available for export from these 

 regions is, for the time at least, approaching its limit — i. e., that only 

 about one-sixth of the wheat produced is available from surpluses 

 in the regions of production for making good deficiencies elsewhere. 



There is, on the other hand, abundant evidence that improved agri- 

 culture is beginning to raise the yield per acre over a large part of 

 the producing area. Between the periods 1881-1890 and 1901-1910 

 the average in the United States rose from 12 to 14 bushels ; in Russia, 

 from 8 to 10; in Australia, from 8 to 10. It is likelj^ that in these 

 last two cases at least a part of the increase is due mereh'^ to more 

 active occupation of fresh lands as well as to the use of more suitable 

 varieties of seed, and the eifect of unprovements in methods of culti- 

 vation alone is more apparent in the older countries. During the 

 same period the average yield increased in the United Kingdom 

 from 28 to 32 bushels, in France from 17 to 20, Holland, 27 to 33; 

 Belgium, 30 to 35 ; and it is most marked in the German Empire, for 

 which the figures are 19 and 29. 



In another important paper ^ Dr. Unstead has shown that the pro- 

 duction of wheat in North America may still in all likelihood be very 

 largely increased by merely increasing the area under cultivation, and 

 the reasoning by which he justifies this conclusion certainly holds 

 good over large districts elsewhere. It is of course impossible, in 

 the present crude state of our knowledge of our own plant, to form 

 any accurate estimate of the area which may, by the use of suitable 

 seeds or otherwise, become available for extensive cultivation. But 

 I think it is clear that the available proportion of the total supply 



^ Geographical .Toumal, April and May, 1912. 



