244 RALPH S. LILLIE AND EARL N. JOHNSTON. 



results in a permanent increase in the quantity of living sub- 

 stance. In the stimulated irritable element (e. g., muscle-cell) 

 growth is not always evident; .but there is evidence that the 

 permeability of the surface-film is increased during stimulation 

 (this structure being apparently broken down or otherwise 

 altered in the stimulation-process), and it seems probable that 

 the normal semipermeable condition is restored by a synthetic 

 process of the kind indicated, and that in this manner the cell 

 regains the resting state. According to this view the altered 

 surface-film is restored to its original or resting state after stimu- 

 lation by a process involving both chemical and structural 

 synthesis, which takes place under the influence of the local 

 biolectric circuit. Presumably repair of the cell-surface after 

 local injury is accomplished in an essentially similar manner. 

 The need of oxygen for the processes of growth, regeneration, 

 or recovery from poisoning, narcosis or over-stimulation (fatigue) 

 may be understood on this general hypothesis; in all such cases 

 oxidation-processes occurring under the control of local bio- 

 electric circuits are necessary for the syntheses involved in the 

 process of construction or restitution. 1 



An instructive physico-chemical analogy is furnished by the 

 local electrochemical reactions concerned in the transmission of 

 the active state over the surface of passive metals, e. g., iron, a 

 process apparently similar in many essential features to proto- 

 plasmic transmission. 2 Here the propagation of the local acti- 

 vation from region to region is directly due to local circuits 

 formed at the boundary between the active and passive areas of 

 the metallic surface; in an iron wire immersed in strong nitric 

 acid the protective or passivating surface-film of oxidation- 

 product is formed at one region of the surface (the anodal) as 

 the activation-wave passes, and broken down by reduction at an 

 adjoining region (cathodal). In such a wire any local inter- 



1 Loeb's observations on the breakdown of the cell-walls in the blastomeres of 

 the Ctenolabrus egg in the absence of oxygen and their re-formation when oxygen 

 is readmitted afford a striking instance of the dependence of structure-formation 

 upon oxidation-processes. Cf. Archiv. f.d. ges. Physiol., 1895, Vol. 62, p. 249; also 

 in "Studies in General Physiology," University of Chicago Press, 1905, Vol. i, 

 P- 370. 



2 Cf. my discussion of this resemblance in Science, loc. cit. 



