ON PHYSICO-CHEMICAL METHODS AND PROBLEMS. I? 



a direct application of the new methods to changes which 

 go on in the organism. These belong more or less in the 

 field of special physiology, while the foregoing fall more 

 naturally into the territory of general physiology. 



We have to deal in what follows almost entirely with 

 the principles of the modern theory of solution, of which 

 extensive use is made in the explanation of phenomena 

 of absorption and secretion. 



We must consider it a great advance that we now know 

 that almost all relations existing between the red blood- 

 corpuscles and the plasma can be explained by the laws 

 which govern any solution. The credit of having recog- 

 nized this fact belongs chiefly to HAMBURGER and KOPPE. 

 These investigations, it seems to me, are the first to 

 conclusively do away with any higher life in the blood. 

 What appears as life in the blood is only a reflection of 

 those true vital processes which go on in the tissues. All 

 known changes which take place in the circulating blood 

 (with the exception of the white blood-corpuscles) are 

 passive physico-chemical reactions, and are in consequence 

 independent of nervous influence. 



Of special physiological and pathological interest are 

 the efforts to explain the activities of the kidneys from 

 these new points of view. The starting-point of these is 

 furnished by a paper of DRESER, in which this author 

 develops for the first time the conception of the osmotic 

 work of the kidneys and calculates this in mechanical 

 work-units. A detailed study of this fundamental con- 

 ception is desirable, since in its original form it is neither 

 entirely clear nor complete. 



We can determine the number of particles present in 

 the unit volume of a solution, the so-called molecular 



