THE PROCESSES OF DEPRESSION 243 



those parts in which oxygen is directly required, is increased by 

 whatever means, the oxydative processes would be the first to fail 

 and it must be from this point that the disturbance of the harmony 

 in the interacting of the individual metabolic processes proceeds. 

 This principle which we here see manifested in its simplest form 

 in the effect of temperature on oxygen exchange in the form of 

 a disturbance in the correlations of the individual constituent 

 processes based on an alteration of the mass relation and the 

 rapidity of reactions of individual members is, however, not 

 merely restricted to effects of temperature and the results quickly 

 following on a relative oxygen deficiency. It has, indeed, a much 

 more general significance for all manner of constituent metabolic 

 processes, for it is applicable to all nutrition and to all growth, 

 and forms one of the most important factors which influence the 

 process of development, that is, the gradual "metachronic" altera- 

 tions in metabolism to which all living systems are subjected as 

 long as life endures. 



A very extensive group of depression processes is produced 

 by the action of chemical stimuli. Among these the processes 

 to which we apply the collective term of "narcosis" must claim 

 our special interest. As is well known, an enormous number of 

 substances of very different chemical nature, such as carbon 

 dioxide, alcohol, ether, chloroform, chloral hydrate, etc., exist, 

 which, possessing the property of producing cessation of the 

 vital activities in all living systems, after withdrawal of their 

 application, if it has not been too prolonged or intense, permit 

 a complete restoration to normal vitality. These are the general 

 narcotics. Besides these there are a series of substances which 

 have a depressing effect only upon certain forms of living sub- 

 stance, and which we may, therefore, term special narcotics. As, 

 however, the particular nature of depression following the 

 application of chemical substances has hitherto been closely 

 studied only in a very few instances, we are not, at present, in a 

 position to sharply define the limitations of the conception of 

 narcosis, a conception which originally had hardly any further 

 meaning than the production of unconsciousness by chemical 

 means. In the following discussion, therefore, we shall deal 



