82 IRRITABILITY 



The increase in volume under the influence of stimuli further 

 shows the relation between the group of those solely catalytic 

 effects of stimulation consisting in mere alterations of rapidity of 

 the specific vital process, and that of the metamorphotic effects 

 of stimulation, which manifest themselves in qualitative altera- 

 tions of the vital process. Simple observation shows us that a 

 qualitative change of individual constituent processes must neces- 

 sarily result from the increase of volume of a cell, and that con- 

 sidering the close correlation of all the individual processes a 

 profound alteration of the entire metabolism must be produced. 

 I have already at another place treated these conditions more in 

 detail and will, therefore, only briefly refer to them here. If we 

 study the growth of a ball-shaped cell, we find that the surface 

 then increases as a square, and the volume as the cube. It there- 

 fore follows that, by progressive volume increase, the conditions 

 for the interchange of substance with the surrounding medium 

 must become more and more unfavorable for those cell portions 

 situated in the interior, whereas those at the exterior are at much 

 greater advantage. This must lead to a constantly increasing 

 difference of the rapidity of the metabolic processes between the 

 peripheral and central portions. Accordingly, the intricate inter- 

 workings of the individual constituent processes, the rapidity of 

 action of all which is intimately connected, are, therefore, fol- 

 lowed by corresponding alterations in the entire metabolism. 

 Sooner or later a stage is reached in which the individual constit- 

 uent processes become so limited that certain metabolic products, 

 which previously were broken down as soon as formed, can be 

 no longer eliminated and remain in the cell acting as foreign 

 bodies. In this way the relative quantity of the individual cell 

 substances become more and more altered, and as the course of 

 chemical processes occurs in accordance with the law of mass 

 action, the whole metabolism is directed into another channel, 

 so that finally new constituent processes take place, which were 

 formerly not possible. These in their turn produce deep-seated 



1 Max Verworn: "Die cellularphysiologische Grundlage des Gedachtnisses." 

 Zeitschrift f. allgemeine Physiologic, Bd. VI, 1907. 



2 Max Verworn: "Allgemeine Physiologie." V. Aufl. 1909, pages 649-671. 



