504 GENERAL PHYSIOLOGY 



associated with the destruction of living substance forms the phase of 

 dissimilation. Assimilation and dissimilation are the basis of all life. 

 Their relation to one another, which was termed biotonus, controls 

 vital phenonema. From the beginning of development to death bioto- 

 nus is constantly changing by reason of individual members of the 

 series of assimilation or dissimilation assuming different values, and 

 thus the details of the vital phenomena likewise change. Biotonus 

 likewise changes if stimuli act upon the living substance, and, 

 accordingly, vital phenomena change under the influence of stimuli. 

 Thus, vital phenomena are determined by the individual links in the 

 long chain of metabolism, which together form the vital process. 



II. The Mechanics of Cell-Life 



After having recognised metabolism as the elementary vital pro- 

 cess, our present task is to derive mechanically from metabolism the 

 vital phenomena, which must be regarded as the expression of the 

 vital process. 



It has been seen that all living substance that now inhabits the 

 earth's surface possesses the form of cells : hence the cell is the pro- 

 per seat of the vital process. In the cell the general vital phenomena 

 are found in their elementary form. If, therefore, their mechanical 

 analysis is not to stop half-way, the cell must be made the object 

 of investigation. Before we can expect to derive the various vital 

 phenomena of the cell mechanically from its metabolism, the 

 question must be answered, hojv the metabolism of living substance, 

 which thus far we have schematically conceived to take place in a 

 uniform substratum, goes on in the cell which possesses the char- 

 acteristic differentiations of its contents. Although with our very 

 slight knowledge of the individual chemical processes in the cell, 

 we are quite unable to picture in detail its more delicate metabolic 

 mechanism, the investigations of the last decade have afforded 

 sufficient material to give an idea of its general metabolic relations. 

 These investigations have revealed a large number of facts, which 

 allow a definite conclusion to be drawn regarding the much-dis- 

 cussed significance of the two essential cell-constituents, the nucleus 

 and the protoplasm, as well as regarding the nature of their relation 

 to one another. 



A. THE ROLE OF THE NUCLEUS AND THE PKOTOPLASM IN THE 

 LIFE OF THE CELL 



1. The Theory of the Dominance of the Nuelcus in the Cell 



The classical researches of the earlier investigators of protoplasm, 

 among whom may be named Dujardin and Max Schultze, were 

 directed toward establishing the protoplasm as the bearer of all 

 vital activities. In the older doctrine of the cell all perceptible 



