172 



Nutritive Matter of Grasses. 



The dry product thus obtained was taken as the measure of the 

 nutritive matter of the specimen examined. 



In this way the greater number of the true grasses and other 

 plants found in or suitable to pastures was carefully examined, 

 and the results were published, as before stated, in Mr. Sinclair's 

 work. There can be no doubt that this method of finding the 

 nutritive matter of the plants afforded data which could not fail 

 to be of value to the intelligent agriculturist, and that it was the 

 best which the state of science at that time could offer, or which, 

 with a moderate outlay of labour, was possible, is sufficiently 

 guaranteed by the name of the great chemist who suggested it. 



But chemistry and physiology have made gigantic strides since 

 that time. We have learnt to separate and identify the chemical 

 principles of which plants are made up, and their composition 

 and properties have been intimately studied. Physiology, on the 

 other hand, has taught us to a considerable extent the part which 

 these principles play in the nutrition of animals. It has shown 

 us that from one is formed flesh, from another fat, whilst to 

 others, again, is allotted the office of supporting respiration and 

 producing animal heat. It is not meant that science was entirely 

 at fault on these points at the period in question, but there can 

 be no doubt that the greater part of our present knowledge of the 

 subject is of a much later date. 



It is, therefore, not to be wondered at, that, with increased 

 knowledge of the offices or functions of vegetable principles in 

 relation to animal life, we should feel the want of a more correct 

 acquaintance with the distribution of those principles in different 

 plants ; and it has been long evident to all who have paid any 

 attention to these subjects, that Mr. Sinclair's determinations of 

 nutritive equivalents for different grasses, however valuable they 

 were at the time when they were executed, are quite unsuitable 

 to our present more advanced stage of knowledge. This is so 

 obvious a fact, that it would be almost unnecessary to occupy the 

 pages of the Journal and the time of the reader in discussing it, 

 were it not that I may at the same time show more plainly the 

 grounds upon which the examination which it is the object of 

 this paper to describe has been based. 



It may be shortly stated that modern chemistry has divided 

 the principles of plants into two great classes — the one including 

 all those vegetable principles which contain nitrogen ; the other 

 comprising those which are destitute of this element. 



The nitrogenous principles are essentially alike in composition, 

 but differ somewhat in properties ; they are know^n as vegetable 

 albumen, casein, legumen, &c. : the first of these is soluble in 

 cold water, but coagulates, and becomes insoluble when the water 

 is boiled ; the two last are insoluble in water either hot or cold. 



