THE RELATIONS OF PHYSIOLOGY 409 



selves not less manifold than those of the great, many-celled or- 

 ganisms. The general physiologic properties of cells must be re- 

 cognized and be distinguished from the specific life-phenomena of 

 separate cell-forms, and this is only possible by use of the compara- 

 tive method. The different sorts of free living and tissue-building 

 cell-forms, from the animal and plant kingdoms, became the objects 

 of physiologic study, and a mass of general physiologic facts resulted 

 from these investigations. The general physics and chemistry of the 

 cell led us deeply into the knowledge of the general phenomena of 

 life. 



But we are only at the beginning. The new discoveries of physical 

 chemistry give, for the analysis of cellular life, new points of view 

 and new methods. The phenomena of assimilation and dissimila- 

 tion, the facts of chemical balance, the disturbances of this balance 

 by external factors, the inner automatic renewing of assimilation, 

 the general effects of irritants, and many other phenomena of general 

 physiology, begin more and more to lift their veils. New expe- 

 riences stream toward general physiology, from the most various 

 sources, which must crystallize themselves around the different 

 parts of the system, after a firm nucleus of phenomena and facts 

 has been determined to connect them. Thus the realm of general 

 physiology grows larger and larger, and begins to break down the 

 isolation of physiology among the biologic sciences. Let us guard 

 the new branch of general physiology from being overtaken by the 

 old fate of physiology, one-sided development. This is only to be 

 avoided if we constantly keep before our eyes its great aim, the 

 mechanical analysis of the general phenomena of life. 



Before all, it is to be desired that general physiology may develop 

 its own special problems as freely as possible, unhindered by atten- 

 tion to special problems and methods. The analysis of the general 

 phenomena of life can easily lead to one-sided methods and one- 

 sided points of view. Even the cellular investigations of general 

 physiologic problems can degenerate selfishly. Here we must be 

 sure to take into consideration the most varying cell-forms, and we 

 must not merely consider individual cells, isolated as such, but also 

 the general relationships and connections which arise from the 

 communistic life of cells and the mutual influence of life-processes 

 in the cell community. The investigation of the dependence of 

 cell-life upon the surrounding life-conditions and the effect of every 

 change of life-condition upon the life of the cell itself is of the 

 greatest importance for the explanation of the immoderately com- 

 plicated processes in the complex organism. 



Also, in regard to methods, there must be no one-sidedness in 

 general physiology. The great results of physical chemistry threaten 

 general physiology with the danger of only working by that method. 



