488 GENERAL PHYSIOLOGY 



With our extremely slight knowledge of the more special trans- 

 formations that take place in living substance, it is at present 

 impossible even approximately to review the manifold possi- 

 bilities resulting from changes of the individual components of the 

 biotonous quotient. Therefore, we shall here refer only to some of 

 the more important of the known cases. 



If the sum of all the members of series A is equal to the sum of 

 series D, i.e., if assimilation and dissimilation are equal in the unit 



A 



of time, the fraction yj=l- This case is realised in the condition 



termed metabolic equilibrium. That is, in the unit of time the sum 

 of the excreted substances of every kind is equal to the sum of the 

 ingested substances. 



If the individual members of series A increase in a constant re- 

 lation to one another, while the members of series D remain equal 

 or decrease, so that in the unit of time the sum of the members of A 

 is greater than that of the members of D, then the metabolic quo- 



tient ->l- This case is realised in growth, where the form- 



ation of living substance surpasses its destruction. 



If, vice versa, the members of series D grow proportionately to 

 one another, while those of series A remain unchanged or become 



A 



smaller, biotonus ^<C1- This condition is the basis of atrophy 



and leads finally to death. 



But it is wholly unnecessary that all members of the one or the 

 other series change always simultaneously and proportionately ; 

 individual members can also increase or decrease independently 

 of the others. Thus, the metabolism of carbon in an organism 

 may be augmented without that of nitrogen experiencing a 

 corresponding increase. In this way occur the formation and accum- 

 ulation of reserve-substances, which are consumed later. Upon such 

 changes of the individual members of the two series depend all the 

 phenomena that appear in an organism in the course of development. 

 In many cases, as is shown best by the changes appearing during 

 development, there exists a certain mutual independence of the 

 individual members of the metabolic series. On the other hand, 

 there are very many cases in which not only the individual 

 members of each series, but also the two series, are dependent upon 

 one another in such a manner that the change of the one results 

 in a similar change of the other. E.g., if there is metabolic 

 equilibrium and the numerator of the fraction increases, the 

 denominator increases equally; if the denominator decreases, 

 the numerator does the same ; in other words, every increase of 

 assimilation results in a corresponding increase of dissimilation. 



A 



In this manner the metabolic quotient -y- remains always equal 



