540 



Ayricultural Chemistry. — Pig Feeding. 



nitrogenous constituents of food, we would at the same time 

 repeat, that by the concurrent testimony of all our feeding 

 experiments, we are led to believe, that on the prevailing views, 

 too high a relative importance is attributed to them. We have 

 thought, therefore, that it would conduce to further progress in 

 this most important field of inquiry, if the current opinions on 

 the subject were somewhat modified. So general indeed has 

 been the adoption, both on the Continent and in this country, 

 of opinions on this subject, for which we have been unable to 

 discern a sufficient basis of facts, and which at the same time, 

 seem to be at variance with the indications of direct experi- 

 ment, that we suppose little apology will be needed, for enter- 

 ing at the length we have done, into questions, which — involving 

 as they do, the very fundamental principles of scientific feeding 

 — appeared to us, to be some of the most interesting and im- 

 portant lessons which our experiments were calculated to 

 teach. 



Postscript. December^ 1853, — Since this Paper was in type, we 

 have had the pleasure of intercourse on some of the points to 

 which it relates, with both Professors Liebig and Boussingault, and 

 we are glad to gather, that they would perhaps somewhat modify 

 the opinions which have generally been attributed to them. M. 

 Boussingault indeed, referred us to the last edition of his ' Eco- 

 nomic Rurale' (Paris 1851), in which both the text and the 

 tables relating to this subject of feeding, have, compared with the 

 edition published some years ago in this country, undergone con- 

 siderable alteration and enlargement. In this new edition, M. 

 Boussingault has clearly pointed out, that the true source of the 

 discrepancy between the practical and theoretical feeding equiva- 

 lents of the Leguminous seeds, depends upon their relatively too 

 small amount of respiratory to nitrogenous constituents. Yet, he 

 still supposes, that the theoretical estimate (i. e., according to the 

 percentage of nitrogen), must be considered as entirely satisfac- 

 tory, when only comparing together foods within the same descrip- 

 tion or class ; the following being the classes he enumerates : — 



" 1. Hays and Straws.", 

 2. Roots and Tubers." 

 " 3. Oleaginous Grains," 

 ; " 4. The Cereal Grains, the Leguminous Seeds, Oilcakes." 



But, it will be seen, that neither the facts, nor the opinions, 

 given in this Paper, are in accordance with this Rule. 



