TRANSACTIONS OF SECTION B. 527 



to that time been conducted, in a paper read before tliis Section of the British 

 Association at the Belfast Meeting in 1852 (and whicli was published in full in the 

 annual volume^), we stated that the mode of estimatin": the amount of proteiiie 

 compounds by multiplying the percentage of nitrogen by 6-3 was far from accurate, 

 especially when applied to succident vegetable foods, and that the individual com- 

 pounds ought to be determined. The Rothamsted Laboratory staff was, however, 

 much smafler then than it is now, and with the pressure of many other subjects 

 upon us, it was at that time quite impossible to follow up the enquiry in that 

 direction. 



It is, indeed, only within the last ten years or so, that the question has been 

 taken up at all systematically ; but we are already indebted to E. Schulze, A. 

 Urick, Church, Sachsse, Maercker, Kellner, Vines, Emmerling, and others, for 

 important results relating to it. 



Our knowledge in regard to the subject is, however, still very imperfect. But 

 it is in progress of investigation from two distinctly ditierent points of ^iew — from 

 that of the vegetable physiologist, and that of' the agricultural chemist. The 

 veo-etable physiologist seeks to trace the changes that occur in the germination of 

 the seed, and during the subsequent life-history of the plant, to the production of 

 seed again. The agricidtural chemist takes the various vegetable products in the 

 condition in which they are used on the farm, or sold from it. And as a very large 

 proportion of what is grown, such as grass, hay, roots, tubers, and various green 

 crops, are not matured productions, it comes to be a matter of great importance to 

 consider whether or not any large proportion of the nitrogenous contents of such 

 products is in such condition as not to be of avail to the animals which consume 

 them in their food ? 



We cannot say that the whole of the nitrogen in the seeds with which we have 

 to deal exists as albuminoids. But we may safely assume that the nearer they 

 approach to perfect ripeness, the less of non-albuminoid nitrogenous matters will 

 they contain ; and, in the case of the cereal grains at any rate, it is probable that if 

 really perfectly ripe they will contain very nearly the whole of their nitrogen as 

 albuminoids. 'With regard to some leguminous and other seeds, which contain 

 peculiar nitrogenous bodies, the range may, however, be wider. 



But whatever the condition of the nitrogenous bodies iii the seeds we grow or 

 sow, with germination begins a material change. Albuminoids are transformed 

 into peptones, or peptone-like bodies, or degraded into various amido- or other com- 

 pounds. Such change into more soluble and more diffusible bodies is, it is to be 

 supposed, essential to their free migration, and to their subserviency to the purposes 

 of growth. In the case of the germination, especially of some leguminous seeds, 

 asparagine has been found to be a very prominent product of such degradation of 

 the albuminoids ; but it would seem that this disappears as the green parts are 

 developed. But now the plant begins to receive supplies of nitrogen from_ the 

 soil, as nitrates or ammonia, and it would seem that amides constitute a consider- 

 able proportion of the produced nitrogenous bodies, apparently as an intermediate 

 stage in the formation of albuminoids. At any rate, such bodies are found to exist 

 largely in the immature plant ; whilst the amount of them diminishes as the plant, 

 or its various parts, approach to maturity. 



But not only have we thus, in unripened vegetable productions, a gr.eater or 

 less, and sometimes a very large, proportion of the nitrogenous bodies formed within 

 the plant, existing as amido-compounds, but we may have a large amount existing 

 in the juices as nitric acid, and some as ammonia. Sec. Thus, E. Schulze determined 

 the nitric acid in various ' roots ; ' and he found that, in some mangolds, more than 

 one-third of the total nitrogen existed in that form, and about one-tenth as much 

 as ammonia. In a considerable series at Rothamsted, we have found an extremely 

 variable proportion existing as nitric acid, according to the size, succulence, or 

 degree of maturity, of the roots ; the amount being, as a rule, the least with the 

 ripest and less highly nitrogenous roots, and the most with the most succulent, 

 unripe, and highly nitrogenous ones. In some cases it reached as much as from 



' ' On the Composition of Foods in relation to Respiration and the Feeding of 

 Animals.' 



