LEGUMINOUS CROPS. 109 



Thus, by the use of 43 lb. of nitrogen as ammonium-salts, 

 there was an estimated increase of 1240 lb. of carbohydrates 

 in the grain and straw of wheat, and of 1992 lb. in those of 

 barley. By the application of 86 lb. of nitrogen as ammonium- 

 salts, there was an increased formation of 2550 lb. of carbo- 

 hydrates in wheat, of 3188 lb. in sugar-beet, of 2376 lb. in 

 mangel-wurzel, and of only 1507 lb. in potatoes ; and when 

 86 lb. were applied as sodium-nitrate, there was an increased 

 production of 3140 lb. in wheat, of 4052 lb. in sugar-beet, of 

 2771 lb. in mangel-wurzel, and of only 1416 lb. in potatoes. 

 Whilst, compared with these amounts, there was by the same 

 application, an increase of only 474 lb. of carbohydrates in 

 beans. 



The last column shows the estimated increased amounts of 

 carbohydrates produced for 1 of nitrogen in manure, in the 

 different cases. Thus, when 43 lb. of nitrogen were applied 

 as ammonium-salts, 1 lb. of nitrogen in manure gave an in- 

 creased production of 28.8 lb. of carbohydrates in the grain 

 and straw of wheat, and of 46.3 lb. in those of barley ; when 

 86 lb. nitrogen were applied as ammonium-salts, 1 lb. gave 

 an increase of 29.7 lb. carbohydrates in wheat, 37.1 lb. in the 

 roots of sugar-beet, 27.6 lb. in those of mangel-wurzel, and 

 17.5 lb. in potatoes. Again, when 86 lb. were applied as 

 sodium-nitrate, 1 lb. gave an increase of 36.5 lb. carbohy- 

 drates in wheat, 47.1 lb. in sugar-beet, 32.2 lb. in mangel- 

 wurzel, 16.5 lb. in potatoes, and only 5.5 lb. in the legumin- 

 ous crops — beans. 



It is natural to ask, What is the explanation of the appar- Seeminaly 

 ently anomalous result, that the crops which are charac- JJJJg"™ 

 terised by containing comparatively little nitrogen, and by plained. 

 yielding large amounts of non-nitrogenous products — starch, 

 sugar, and cellulose — are especially benefited by the applica- 

 tion of nitrogenous manures ; and that, under their influence, 

 they yield greatly increased amounts of those non-nitrogenous 

 bodies ? 



It is, perhaps, little more than stating the facts in another 

 way to say, as is the case, that the luxuriance or activity of 

 growth of all these crops is very greatly enhanced by nitro- 

 genous manures ; and that, since their special products are 

 these non-nitrogenous substances, the natural result of the 

 increased luxuriance is to increase the formation of the 

 bodies which are their essential or characteristic products. 



A further possible explanation of the curious result has, 

 however, been suggested. 1 



Thus, on purely chemical and physiological grounds, and 



1 See Vines' Lectures on the Physiology of Plants, p. 140 et seq. 



