The Eothamsted Experiments. 



with different manures have also been made, on other descrip- 

 tions of soil, at Holkham and Eodmersham. Samples of the 

 soils, of the crops, and of different portions of the crops are 

 taken to the laboratory and subjected to exhaustive chemical 

 analysis, and it is on the results of such examinations that 

 the conclusions are based. Other inquiries have embraced 

 the investigation of soils, especially with reference to the per- 

 centages of nitrogen they contain at different depths, the 

 chemical constituents in rain and in drainage waters, the 

 amount of water transpired by plants, and experiments on 

 the assimilation of free nitrogen by vegetation. 



Equally important experiments with farm animals were 

 commenced in 1847. Among the points which have been 

 investigated are : (1) The amount of food, and of its several 

 constituents, consumed in relation to a given live-weight 

 of animal within a given time. (2) The amount of food, 

 and of its several constituents, consumed to produce a given 

 amount of increase in live-weight. (3) The proportion, and 

 relative development, of the different organs or parts of 

 different animals. (4) The proximate and ultimate com- 

 position of the animals in different conditions as to age and 

 fatness, and the probable composition of their increase in 

 live- weight during the fattening process. (5) The com- 

 position of the solid and liquid excreta (the manure) in 

 relation to that of the food consumed. (6) The loss or ex- 

 penditure of constituents by respiration and the cutaneous 

 exhalations that is, in the mere sustenance of the living meat- 

 and-manure-making machine. Oxen, sheep, and pigs have 

 been the subjects of the experiments, and the results obtained 

 have further been of use in furnishing data for the con- 

 sideration of the following questions : (1) The characteristic 

 demands of the animal body (for nitrogenous or non- 

 nitrogenous constituents of food) in the exercise of muscular 

 power. (2) The sources in the food of the fat produced in 

 the animal body. (3) The comparative characters of animal 

 and vegetable food in human dietaries. 



