114 GRASSES AND FORAGE PLANTS. 



which is found to be an ingredient of most vegetable substances 

 at some periods of their growth, in some degree contributes to 

 it also. The nitrogenous constituents of any substance, as 

 grass or hay, for instance, may be determined with little diffi- 

 culty and with great exactness, since it has been found by 

 abundant research, that, when present, they are of nearly the 

 same constitution, and do not vary in their combinations. The 

 determination of the sugar is somewhat more difficult. 



The constituents of plants may be divided into two classes, 

 one class embracing all those sul)stances of which nitrogen or 

 azote forms a part, and the other consisting of non-nitrogenous 

 bodies. Gluten, albumen, gelatine, casein, legumen and fibrin, 

 belong to the former class, being nitrogenous substances, while 

 starch, gum, sugar, woody fibre, mucilage, <fec., are destitute of 

 nitrogen, or non-nitrogenous. 



Only a small quantity of nitrogen is found in vegetable sub- 

 stances, and it is derived, in part, at least, from the atmosphere 

 in the form of ammonia. On the other hand, nitrogenous sub- 

 stances form a large proportion of the constituents of the blood 

 of animals and appear in their whole system. As there is a con- 

 stant waste in the animal and a continual formation of new 

 tissues, — as the whole body is constantly renewed through the 

 agency of the blood which is converted into flesh and muscle, — 

 there must be a never failing supply of nourishment, and this 

 nourishment for the higher animals is found, as already inti- 

 mated, in the nitrogenous elements of plants. 



conducted by his gardener, George Sinclair, were detailed in a volume under 

 the title of " Ilortus Gramineus Wohurnensis." This Avork, which was the 

 first treatise worthy of mention on this subject, became the text-book on the 

 grasses, and has been followed by most subsequent writers, down to the present 

 time. But these experiments must be regarded as very unsatisfactory, both 

 on account of the imperfections of the methods of arriving at the results, 

 (though they were the best then known, and suggested by Sir Humphrey 

 Davy,) and because each species or variety was cultivated only to a very limited 

 extent. The produce per acre, for instance, was calculated, in most cases, 

 from the jield of four square feet. Besides this, very great discrepancies 

 occur in the volume which can with difficulty be accounted for. 



The analyses recently made by Prof. Way, the distinguished chemist of the 

 Royal Agricultural Society, arc more reliable, in my estimation, than any 

 which can be found, and no treatise on the grasses would be complete without 

 giving the valuable results to which he has arrived. 



