The Functions of the Blood. 93 



materials, could only yield about 30,000 metre- kilogrammes of 

 force. 



Now the daily work of tlie heart alone is estimated by 

 Ponders at 86,000 metre-kilogrammes, and it is an extreme 

 under-statement to assert that the total daily work of the body 

 in health is 100,000 metre-kilogrammes. To do even this 

 quantity of work, twice the quantity, or 200,000 metre-kilo- 

 grammes of force must, as Heidenhain has proved, be pro- 

 vided ; so that even taking the highest possible calculation of 

 the quantity of oxygen which could pass into the tissues, we 

 see that it cannot account for one-sixth of the work done in 

 them. It is more probable, indeed, that it cannot account for 

 one- sixtieth. To supply the minimum force per diem exerted 

 in the body, there must be a daily exudation of about 



264 litres, or j-ton, if the exudate contains as much oxygen as 



arterial corpuscles; or, 

 3500 litres, or 3* -tons, on the more probable supposition that 



it will not dissolve more than water will. 



These figures appears to me to furnish a complete answer to 

 the current theory of tissue-oxidation, and to force us inevitably 

 to the conclusion so clearly pointed out by Mayer, namely, that 

 the whole, or nearly the whole, of the animal oxidation, is 

 effected in the blood itself, and consequently that there must 

 exist some provision by which chemical force set free inside a 

 capillary is converted into mechanical work in the tissues 

 outside of it. 



This view of the nature of animal oxidation tends to define 

 more clearly our knowledge of the functions of the blood. 

 Nutrition is one of its functions. It carries with it in its 

 course the appropriate pabulum for the repair of all the tissues 

 of the body. Bones, nerves, glands, and muscles, all alike 

 reproduce their elementary parts at the expense of material 

 derived from its fertilizing stream. And as these elementary 

 parts attain their term of life they decompose and liquefy, 

 passing again into the blood, for the most part through the 

 same lymphatic vessels which take back the excess of the 

 nutritive fluid. In the lymphatic vessels and glands much of 

 the lymph is once more organized into blood, but the products 

 of the disintegration of tissue are probably incapable of this 

 renewal, and, in the absence of evidence must be supposed to 

 return into the blood in an unorganized condition. 



Equally important with the foregoing is the function of 

 oxidation, to which the force as well as the heat of the body is 

 due. Nitrogenous as well as non-nitrogenous bodies are 

 oxidized in the blood, and though we do not yet know the 

 precise conditions or the precise mode in which the oxidation 



