528 EEPORT — 1880. 



20 to nearly 30 per cent, of the total nitrogen. In many other immature vegetable 

 products nitric acid and ammonia have been found ; but, so far as 1 remember, in 

 none in anything like so large a proportion as in the so-called ' root-crops,' es- 

 pecially manoglds. In many, however, the quantity appears to be immaterial ; and 

 it is remarkable that whilst thei-e is so much in the ' roots,' little or none is found 

 in potatos. 



No wonder that, in the experiments already referred to, we foimd the feeding 

 result to be the worse the more succulent and immature the roots, and the higher 

 their percentage of nitrogen, accordingly. 



But it is to the difference in amount of the albuminoid bodies themselves, in 

 different descriptions of vegetable produce, that I wish specially to direct attention, 

 making, however, some reference to what is known of the proportion of the 

 nitrogen existing as amido-compounds. 



In some mangolds E. Schulze found only from about 20 to 22 per cent, of their 

 total nitrogen to exist as insoluble and soluble albumin. But he found in one case 

 32*5, aud in the other 408, per cent, of the total nitrogen as amides. In a large 

 series of determinations at Eothamsted, by Church's method, we found a variation 

 of from under 20 to over 40 per cent, of the total nitrogen of mangolds to exist as 

 albuminoids ; or, in other words, from nearly 60 to over 80 per cent, of it in the 

 non-albuminoid condition. 



In potatos Schulze foimd from under 50 to Go per cent, of the total nitrogen 

 as soluble and insoluble albumin, and from 27'7 to 49-1 per cent, as neutral and 

 iicid amides. In a series of potatos grown at Rothamsted, under very various 

 conditions as to manuring, and in two different seasons, we found the nitrogen as 

 albuminoids to range from little over 50 to more than 71 per cent, of the total 

 nitrogen ; leaving, of course, from less than 30 to nearly 50 per cent, to be 

 accounted for in other ways. 



Kelbier determined the amount of nitrogen as albuminoids, and as amido-com- 

 pounds, in a considerable series of green foods, both leguminous and gramineous, cut 

 at different stages of their growth. The proportion of the total nitrogen not as 

 albuminoids was, upon the whole, greater in the leguminosje than in the graminese. 

 In both, however, the proportion as albuminoids increased as the plants approached 

 to maturity. The proportion as albuminoids was in all these products very much 

 larger than in roots, and generally larger than in potatos. In the case of first-crop 

 meadow hay, we found in the separated gramineous lierbage 76'4, in the leguminous 

 herbage 82, and in the miscellaneous herbage 80'3 per cent of the nitrogen as 

 albuminoids ; and in the second crop 86'2 per cent, in the gramineous, 88"3 per 

 cent, in the leguminous, and 88T per cent, in the miscellaneous berbage. How far 

 the higher proportion of the nitrogen as albuminoids in the second crops is to be 

 taken as any indication of the characteristics of the autumn growth, or how far it is 

 to be attributed to the accidental condition of the weather, may be a question. 



These illustrations are sufficient to give some idea of the range and proportion 

 of the nitrogen in different feeding crops which does not exist as albuminoids ; and 

 they are sufficient to show that a very large proportion of the non-albuminoid 

 matter exists as -N'arious amido-compounds. The question arises, therefore, whether 

 these bodies contribute in any way to the nutrition of the animals which feed upon 

 them ? We have but little experimental e\-idence on this point. As green herbage 

 is the natural food of many descriptions of animal, we might suppose that charac- 

 teristic constituents of it would not Ije without some value as food ; but the culti- 

 vated root crops are much more artificial productions, and it is in them that we 

 find such a very large proportion of non-albuminoid nitrogen. With respect to 

 some of the amido-compounds, at any rate, direct experiments seem to show that 

 they are digested in the animal body, and increase the elimmation of urea. Weiske 

 and Schrodt found that rabbits receiving, as their only nitrogenous food, either 

 asparagine or gelatin, wasted and died ; but a rabbit receiAdng both asparagine and 

 gelatin increased in weight and survived to the end of the experiment, which 

 lasted seventy-two days. From the results of other experiments made with sheep, 

 they concluded that both asparagine aud gelatin protect the albuminoids of the 

 bodv from oxidation. 



