88 PHYSIOLOGY CHAP. 



different constitution. In order to distinguish this body, there- 

 fore, from dead protein, and to indicate its high significance in 

 the occurrence of vital phenomena, it appears fitting to replace 

 the term ' living protein ' with that of biogen. The expressions 

 'plasma molecule/ 'plasson molecule/ 'plastidule/ etc., which 

 Elsberg and Haeckel have employed, and the conceptions of 

 which are comprised approximately in the expression 'biogen 

 molecule/ are less fitting in so far as they easily give the 

 impression that protoplasm is a chemically unitary body, which 

 consists of wholly similar molecules; such a view must be ex- 

 pressly rejected. Protoplasm is a morphological, not a chemical 

 conception." 



Verworn gives the name of Biotonus to the ratio between the 

 assimilatory and dissirnilatory processes, which Hering, as we have 

 seen, regards as the theoretical foundation of the processes that go 

 on in living matter. 



" If we consider," he goes on, " the quantitative relation of 

 assimilation to dissimilation in a considerable mass of living 

 substance, such, for example, as is contained in a cell, we find it 

 very variable, and even without the influence of stimuli it changes 

 within wide limits. This relation of the two processes in the unit 



of time, which can be expressed by the fraction =- and will be 



termed, in brief, biotonus, is of fundamental importance for the 

 various phenomena of life. The variations in the value of the 

 fraction effect all changes in the vital manifestations of every 

 organism. 



" The fraction j - is merely a general form of the expression 



of biotonus. In reality, assimilation and dissimilation are not 

 simple processes; on the contrary, the events that lead to the 

 construction of the biogen molecule, and the formation of the 

 decomposition-products, are very complex and consist of processes 

 closely interwoven. Hence if we would express biotonus in a 

 specialised way, we must give the fraction the form 



a + & 



d + rfj + d. 2 



in which a, a v a. 2 , a 3 , etc., and d, d v d 2 , d 3 , etc., represent the 

 partial processes that combine to form the" whole." 



With our present limited knowledge of the more special 

 transformations that take place in living substance, it is impossible 

 approximately to gauge the significance of the individual com- 

 ponents of the biotonous quotient. Verworn, therefore, refers 



only to considerations arising from the general formula ^. 



Where assimilation and dissimilation are equal in the unit of 



