338 



THE KOTHAMSTED EXPERIMENTS. 



Rotliam- 

 sted re- 

 searches. 



be so identified for many years. Thus, Professor Frankland, 

 in his lecture at the Eoyal Institution in 1866 x on the ex- 

 periments of Tick and Wislicenus, 2 refers to these views of 

 Liebig as having, up to that time, been pretty generally 

 adopted by text-book writers. 



The results of our own feeding experiments, which were 

 commenced some years after the appearance of Liebig's work, 

 being apparently inconsistent with the then current views on 

 some important points, we were led at once to turn attention 

 to the subject of human dietaries ; and also to a consideration 

 of the management of the animal body undergoing somewhat 

 excessive labour, as for instance, the hunting-horse, the racer, 

 the cab-horse, the fox-hound, and also pugilists and runners. 

 The conclusions to which we were led by this study were 

 briefly summarised in a paper published in the Report of the 

 British Association for the Advancement of Science, for 1852, 

 as follows : — 



Conclu- 

 sions of 

 1852. 



Respir- 

 atory ma- 

 terial and 

 muscular 

 force. 



. . . that in the cases, at least of ordinary exercise of force, the exi- 

 gencies of the respiratoiy system keep pace more nearly with the de- 

 mand for nitrogenous constituents of food than is usually supposed ; 

 and further : — 



A somewhat concentrated supply of nitrogen does, however, in some 

 cases, seem to be required when the system is overtaxed ; as for in- 

 stance, when day by day more labour is demanded of the animal body 

 than it is competent without deterioration to keep up ; and perhaps 

 also, in the human body, when under excitement or excessive mental 

 exercise. It must be remembered, however, that it is in butcher's meat, 

 to which is attributed such high flesh-forming capacity, that we have 

 also, in the fat which it contains, a large proportion of respiratory 

 material of the most concentrated kind. It is found, too, that of the 

 dry substance of the egg, 40 per cent is pure fat. 



A consideration of the habits of those of the labouring classes who 

 are under- rather than over-fed, will show that they first have recourse 

 to fat meat, such as pork, rather than to those which are leaner and 

 more nitrogenous ; thus perhaps indicating, that the first instinctive 

 call is for an increase of the respiratory constituents of food. It cannot 

 be doubted, however, that the higher classes do consume a larger pro- 

 portion of the leaner meats ; though it is probable, as we have said, 

 that even with these as well as pork, more fat, possessing a higher re- 

 spiratory capacity than any other constituent of food, is taken into the 

 system than is generally imagined. Fat and butter, indeed, may be 

 said to have about twice and a half the respiratory capacity of starch, 

 sugar, &c. It should be remembered, too, that the classes which con- 

 sume most of the leaner meats, are also those which consume the most 

 butter, sugar, and in many cases, alcoholic drinks also. 



It is further worthy of remark, that wherever labour is expended in 

 the manufacture of staple articles of food, it has generally for its object 

 the concentration of the mow-nitrogenous, or more peculiarly respiratory 

 constituents. Sugar, butter, and alcoholic drinks are notable instances 



1 Journ. R. Inst., 1866. 



2 Phil. Mag., 1866, 4th series, vol. 31, pp. 485-503. 



