62 



THE ROTHAMSTED EXPERIMENTS. 



the larger the amount of nitrogen supplied, but by no 

 means in proportion to the amount supplied. The effici- 

 ency of a given amount of nitrogen is greatly dependent on 

 the completeness of the accompanying mineral supply, and 

 especially on that of potash. Again, the greater the excess 

 of nitrogen, the greater the luxuriance, and the less ripe 

 the roots, the less is the amount of sugar obtained for a 

 given amount of nitrogen supplied. Lastly, it will be re- 

 membered that with sugar-beet much more sugar was ob- 

 tained for a given amount of nitrogen in manure than the 

 above figures show was the case with the mangel-wurzel. 



SUGAR FOR 1 OF POTASH IN THE ROOTS. 



Albumin- 

 oids and 

 amides. 



Nitric acid 

 and am- 

 monia. 



Condition of the Nitrogen in Roots. 



An important point yet to consider is the amount and 

 the condition of the nitrogen in roots of different descrip- 

 tions, or grown under different conditions. 



As is well known, in perfectly ripened seeds by far the 

 larger proportion, and in many cases nearly the whole, of 

 the nitrogen exists as albuminoids. In ripened products, 

 however, some, and in unripened ones sometimes a large 

 proportion, of the nitrogen exists as amides. Now, so far 

 as present knowledge goes, it seems probable that it is only 

 the nitrogen existing as albuminoid compounds that can 

 contribute to the formation of the albuminoid compounds 

 of animal bodies, or of milk. It would seem not improbable, 

 however, that some amide compounds may replace the albu- 

 minoids in supplying material for the transformations inci- 

 dent to the constant waste of the nitrogenous substances of 

 the body, the products of which pass from it in the urine. 



Then, again, besides albuminoids and amides, succulent or 

 immature vegetable products may contain nitrogen as nitric 

 acid, or as ammonia, unchanged from the condition in which 

 it has been taken up by the roots of the plant from the soil, 

 or the one transformed into the other. 



The question as to the condition of the nitrogen in 

 vegetable foods, and especially in such crude and immature 



