412 PHYSIOLOGY 



titative or qualitative change of the existing processes of life. The 

 latter group of effects is less extended in the normal life of the 

 adult organism, and until now has been least studied. It appears, 

 however, as far as we can determine from an extensive analysis, 

 only as a secondary result of primary stimulation of the first group. 

 The great mass of stimuli in the course of the life of the normal 

 organism only cause quantitative changes of phenomena already 

 existing in the living system, i. e., either an increase of the same 

 (excitement), or a decrease (paralysis). 



The analysis of the effects of stimulation has now gone much 

 further. I must, however, limit myself to-day to the most gen- 

 eral indications. I will only be able to show how extraordinarily 

 important this analysis is for the basic question of medicine, what 

 is disease? Disease is nothing else than life under changed ex- 

 ternal relationships, i. e., life under the influence of stimuli. Thus, 

 pathology comes finally to be a study of the effect of stimuli, and 

 it needs no argument to show that the physician cannot pene- 

 trate too deeply into the knowledge of the effects of stimulation 

 and the laws governing them. Above all, medical diagnosis, which 

 by many physicians is considered the most important part of medi- 

 cine, requires a comprehensive knowledge of the laws of stimuli. 

 The physician must ask himself at the sick bed, what part of the 

 organism is primarily affected by a stimulus? Does the effect con- 

 sist in a quantitative change, an excitement or paralysis, or in a 

 qualitative change of the normal life-processes? How may this 

 change of the affected part act upon neighboring or distant parts 

 of the body, as a result of the correlation of all the elements in 

 the body, and how will the entire vital mechanism of the organism 

 be disturbed? Those are the fundamental questions which every 

 physician must lay before himself in a given case, if he wishes to 

 have a fitting conception of the disease. Only then can he use his 

 therapeutic means effectually. But it is not necessary for me to 

 emphasize that this analysis must proceed as far as the cells them- 

 selves. A greater than I, almost a century ago, demonstrated so 

 convincingly this requirement of pathology, that our entire present- 

 day medicine rests upon the basis of cellular pathology. Since 

 the epoch-making work of Rudolph Virchow, cellular pathologic 

 investigation has developed almost exclusively toward the side 

 of morphology, not toward that of physiology. A picture of a mi- 

 croscopic preparation of the diseased part, beautifully colored, 

 with red or blue nuclei, etc., floats before the eyes of the well-edu- 

 cated physician, at the sick-bed. It does not occur to him, how- 

 ever, that the cells which he sees in imagination are alive, and 

 he overlooks completely the chemistry of healthy and diseased 

 cells. This is the place where general cellular physiology must 



