114 HOW CROPS GROW. 



AVEKAGE QUANTITY OF ALBtTMINOEDS IN VAKIOUS VEGETABLE 

 PKODUCTS.— ALBUMINOIDS = N X 6.25. 



American, Jenkins. German, Wolff. 



Maize fodder, green 1.8 1.9 



Beet tops, " 2.7 3.0 



Carrot tops, " 4.3 5.1 



Meadow giass, in bloom 3.1 4.8 



Eed clover, " 3.7 4.8 



Wliite clover, " 4.0 5.6 



Turnips, fresli 1.1 1.8 



Carrots, " 1.1 2.2 



Potatoes, " 2.2 3.4 



Com cobs, air-dry 2.3 2.3 



Straw, " 3.5 4.0 



Pea straw, " 7.3 10.4 



Bean straw, " 10.2 16.3 



Meadow hay, in bloom 7.0 15.5 



Eed-clover hay, " 12.6 19.7 



White-clover hay, " 14.6 23.2 



Bnekwheat kernel, air-dry 10.0 14.4 



Barley " " 12.4 16.0 



Maize " " 10.6 16.0 



Eye " " 10.6 17.6 



Oat " " 11.4 17.6 



Wheat " " 11.8 . 20.8 



Pea " " 22.4 35.8 



Bean " " 24.1 40.8 



The Amides, Amidoacids, Imides, and Amines. 

 — Ammonia and the ammonium salts, so important as 

 food to plants, and as ingredients of the atmosphere, of 

 soils, and of manures, occur in so small proportions in 

 living A'egetation as to scarcely require notice in this 

 work occupied with the composition of Plants. They 

 are, however, important in connection with the amides 

 now to he briefly described. Ammonia, an invisible gas 

 of pungent odor which dissolves abundantly in water to 

 form the aqua ammonia of spirits of hartshorn of the 

 apothecary, is a compound of one atom of nitrogen with 

 three atoms of hydrogen. It unites to acids, forming 

 the ammonium salts : 



^f moderate fertility, both ammonia and nitric acid, or strictly speak- 

 ing, ammonia-salts and nitrates, commonly occur in very small pro- 

 portions. In roots, stems, and foliage of plants situated in soils rich 

 in these substances, they may be present in notable quantity. The 

 dry leaves and stems of tobacco and beets sometimes contain several 

 per cent of nitrates. When these substances are presented to plants in 

 abundance, especially in dry weather, they may accumulate In the 

 roots and lower parts of the plant more rapidly than they can be assim- 

 ilated. On the other hand, when their supply in the soil is relatively 

 small they are so completely and rapidly assimilated as to be scarcely 

 detectable. Their possible presence should be taken into account when 

 it is undertaken to calculate the albuminoids of the plant from the 

 amount of nitrogen found in its analysis. 



