30 IRRITABILITY 



this, however, it is essential that we study the conditions already 

 existent in the entire system previous to the action of the 

 stimulus. 



That which we describe with the word life is an exceedingly 

 complex process. If we analyze life, it is found to be composed 

 of an immense number of separate constituent processes, each 

 one being conditioned by the others. These constituent pro- 

 cesses are the vital conditions. A vital process occurs, and must, 

 occur, where and when the whole sum of vital conditions is 

 realized. It is identical with the sum total of the vital condi- 

 tions. If only one condition is absent, then life does not exist. 

 It is then expedient to reserve the expression "life" for the 

 entire sum of the vital conditions. When we speak of the indi- 

 vidual constituent processes as "vital processes" in the plural, 

 we must bear in mind that in reality each is not in itself life. 

 Only the whole complex "lives," not an individual constituent 

 of the same. Living substance is rather the whole system, and 

 not a constituent part of the same, not a piece of protoplasm, not 

 a nucleus and not a specific protein combination in the cell. 



A property of this system should receive our consideration at 

 this point. It is a characteristic of every system in the world, 

 namely, the fact that a system is not isolated from its surround- 

 ings. It is a deception resulting from the selective action of our 

 sensory organs, if we consider the bodies as separated and iso- 

 lated from their environment. This deception disappears upon 

 further analysis and when we assist our organs of sense, which 

 only respond to certain parts of the whole process, by experi- 

 mental methods of investigation. Our experience then shows 

 us that an isolated system does not exist, but that there are 

 instead everywhere connections which extend further and fur- 

 ther into the infinity of the world. An organism is consequently 

 no deliminated system and the vital process cannot, therefore, be 

 sharply separated from the processes in the medium. We can- 

 not draw a sharp line between vital processes and say: on the 

 right we have factors which are necessary for the maintenance 

 of life, and on the left factors which are not necessary. The 

 conditional connection between individual processes extends to 



