334 



THE ROTHAMSTED EXPERIMENTS. 



Further 

 experi- 

 ments in 

 Germany. 



Nitrogen 

 of the food 

 entirely re- 

 appearing 

 in excre- 

 ments. 



rnent in methods of collection, sampling, preparation, and 

 analysis. 



For ourselves, being satisfied that much if not the whole 

 of the losses that had been indicated was to be explained by 

 the methods of experimenting, and being very fully occupied 

 with other subjects, we decided, after our experiments with 

 pigs in 1862, not to devote the very great amount of time 

 and labour that would be involved in the repetition of the 

 investigation with still further precautions. 

 , In Germany, however, Henneberg and his colleagues (G. 

 Kuhn, H. Schultze, and B. Schultz), at Weende, as well as 

 others, continued to work on the subject with the animals of 

 the farm. Henneberg l pointed out that the experiments of 

 Bischoff and Voit with dogs in 1859, 2 of Ranke with man in 

 1860-61, 3 of Voit with pigeons in 1860-62, 4 and of Petten- 

 kofer and Voit with man, 6 showed almost complete re-appear- 

 ance of the nitrogen of the food in the solid and liquid excre- 

 tions ; and, if this were the case with carnivora and omnivora, 

 there seemed no reason why it should not be so with herbi- 

 vora. He further pointed out how small an actual loss or 

 gain in the determined amount of nitrogen in the fasces or 

 the urine might make a great difference in the balance ; and 

 he admitted that more attention than had hitherto been given 

 to certain points must in future be devoted — as, for instance, 

 to the rinsing and washing of the stalls, and to the determin- 

 ation of the dry matter in the food, fasces, and urine, more 

 frequently and uniformly throughout the experimental period. 



In the Weende experiments of 1865, and subsequently, 

 more attention was paid to such points, and the periods of 

 exact experiment were longer. There was, accordingly, great 

 improvement in the results. Thus, in a series of eight experi- 

 ments with oxen, in five with only sustenance or maintenance 

 rations, the result was that, in three of them the percentage 

 deficit of nitrogen in the excrements compared with that in 

 the food was 0.4, 2.7, and 2.2. ; whilst in the other two there 

 was a gain representing 0.8 and 3.7 per cent. In the three 

 other experiments, fattening food containing about twice as 

 much nitrogen was given, and in these the deficits in the 

 excrements were 12.1, 12.0, and 17.7 per cent of the nitrogen 

 in the food. Henneberg concluded that, with only susten- 

 ance rations, the whole of the nitrogen of the food of oxen 

 reappeared in the excrements, and that it was no longer 



1 Neue Beitrdge, Gottingen, i. 373-375, 1872. 



2 Die Gesetze der Ernahrung des Fleischfressers, Leipzig, 1860. 



3 Archiv fur anat., phys. und wissenschaftliche Medicin, Leipzig, 1862, p. 

 311. 



4 Annalen, II. Suppl. p. 238, 1862. 



5 Zeits.f. Biol., II. p. 459. 



