THE HISTORY OF THE SUBJECT 11 



that a process of formative change may occur which produces 

 new elements in greater or less numbers. Virchow touches here 

 for the first time upon a question of extraordinary moment, the 

 important bearings of which have only now begun to be recog- 

 nized and seriously considered. We now know, for example, 

 that the functional excitation can be separated to a certain degree 

 from the cytoplastic excitation of the muscle. If the muscle is 

 acted upon by functional stimuli, the excitation takes place mainly 

 in the form of functional metabolism, nitrogen-free substances 

 are broken down in increased quantities, whereas cytoplastic 

 metabolism, which produces more profound alteration in the living 

 substance, and which goes so far as to bring about a breaking 

 down and building up of the nitrogen containing atom groups, is 

 hardly at all increased. It would be an error, however, to look 

 upon these different kinds of metabolism as quite independent. 

 Considering the close correlation which all the phases of metab- 

 olism bear to each other, this idea cannot well be entertained. 

 If, however, we question in what manner, for instance, the 

 functional and the cytoplastic metabolism are linked together, 

 we have a problem before us which does not belong to the past, 

 but to the present and future. Indeed, Virchow seems already to 

 have felt that a sharp division between the different phases 

 and parts of functional metabolism in the cell does not exist, for 

 he says: "It is true that it cannot be denied that, especially be- 

 tween the nutritive and formative processes and likewise between 

 the functional and nutritive, intermediate gradations occur." Still 

 they differ essentially in their characteristic action and in the 

 internal alterations which the stimulated part undergoes, depend- 

 ing on whether it functionates, nourishes itself, or is the seat of 

 special growth. Disease consists of the influence of stimuli upon 

 these physiological processes. The law of the specific energy of 

 living substance is as clearly expressed in functional disease as it 

 is in the physiological effects of stimuli. The pathological dis- 

 turbance of function is purely quantitative, "nowhere is there a 

 qualitative divergence." The function exists or it does not exist. 

 If it is present, it is either strengthened or weakened. This gives 

 the three fundamental forms of disturbance : absence, weakening 



