OF AGRICULTURE. 23 



and the quantity of living tissue transformed, as 

 proportional to the quantity of oxygen inspired and 

 consumed in a given time by the animal.' 



And again : — 



■ The production of heat and the change of matter 

 are closely related to each other ; but although heat 

 can be produced in the body without any change of 

 matter in living tissues, yet the change of matter 

 cannot be supposed to take place without the co- 

 operation of oxygen/ 



Further, on the same point : — 



' The sum of force available for mechanical purposes 

 must be equal to the sum of the vital forces of all 

 tissues adapted to the change of matter.' 



' If, in equal times, unequal quantities of oxygen are 

 consumed, the result is obvious, in an unequal amount 

 of heat liberated, and of mechanical force.' 



' When unequal amounts of mechanical force are 

 expended this determines the absorption of corres- 

 ponding and unequal quantities of oxygen.' 



Then, more definitely still, referring to the changes 

 which take place coincidently with the exercise of 

 force, and to the demands of the system for repair 

 accordingly, he says : — 



1 The amount of azotised food necessary to restore 

 the equilibrium between waste and supply is directly 

 proportional to the amount of tissues metamorphosed.' 



* The amount of living matter, which in the body 

 loses the condition of life, is, in equal temperatures, 

 directly proportional to the mechanical effects pro- 

 duced in a given time/ 



s The amount of tissue metamorphosed in a given 

 time may be measured by the quantity of nitrogen 

 in the urine.' 



' The sum of the mechanical effects produced in 



