SOME OF THE AHIMAES FED AND SLAUGHTERED AS HUMAN FOOD. 495 
Physiologist, in determining the relations of the system, to the matters ingested as food ; 
nor is such knowledge an unimportant element in studying the changes which the 
latter undergo, and the offices they subserve, in their passage through the body. 
Especially, is a knowledge of the general composition of the animals slaughtered as 
human food, of great importance in the application of Chemistry and Physiology to 
Dietetics. This, indeed, is a branch of applied physiology, so to speak, which, owing in 
great part to the attention drawm to it by the labours of Boussingault, Muldee, and 
Liebig, from fifteen to twenty years ago, may be said to have entered upon a new era 
about that period. It is, moreover, daily gaining ground, both with the Physician and 
the Economist. To the Farmer, too, who is engaged in producing animal food for the 
consumption of the community at large, it is very desirable to know something of the 
chemical relations of the substance so produced and sold, to the constituents expended 
in producing it. In other words, he should possess some data for determining — what is 
the probable proportion of the consumed food, or of its several constituents, which he 
recovers in the form of meat \ — how much he may calculate as manure I — and how much 
as expendiUire or loss by the feeding process 1 
It is ob\ious, that these comprehensive factors involved in the great question of animal 
nutrition, may be sought, individually, or collectively, and in various ways. For valu- 
able contributions on special points, we are indebted to Duloxg and Despeetz, to Allex 
and Pepys, to Dumas and Milne-Edwaeds, to Axdeal and Gavaeeet, to Begiyault and 
KeISET, to COATHUPE, SCHAELIXG, ViEEOEDT, MaECHAND, BeCQUEEEL, LeCANU, ChOSSAT, 
Bischofp, Peesoz, and others. For the study of the subject in its more collective form, 
we are indebted, more particularly, to Fixing, to Dalton, to Boussingault, to Liebig, 
to Platpaie, E. D. Thomson, Payen, Valentin, Simon, Biddee and Schmidt, Bakeal, 
and Lehmann. So far as the animals of the farm are concerned, the labours of Bous- 
singault, E. Wolff, Eitthausen, and FIennebeeg, stand prominent for persevering 
experimental research ; whilst to Liebig we owe much for the stimulus given, and the 
discussion incited, by his generalizations on various branches of animal chemistry. To 
Lehmann again, independently of his own original researches, we are indebted for a 
systematic review of the labours of others ; and we are glad to have the sanction of one 
who has ably executed the task herein implied, to the importance, under the existing 
conditions of our knowledge, of the statistical method of inquiry. Thus, he says 
As long as zoo-chemistry and the theory of the juices continue to occupy their pre- 
sent subordinate position, the only method by which the foundation necessary to an 
exact investigation can be obtained is that which we may term the statistical. Liebig, 
Boussingault, and Valentin have indeed, with a more correct view of what was 
required, attempted to compare the .final efiects of the whole with the material sub- 
strata supplied to the organism. We cannot, it is true, arrive at any conclusion 
regarding the working of the process itself by a mere juxtaposition and quantitative 
comparison of the ingesta and excreta of the animal organism, any more than we can 
.ffi ge of the causes and course of diseases by the number of fatal cases recorded; but 
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