l6O RALPH S. LILLIE. 



ment of the electrical circuit. As the current flows, structural 

 material is formed and deposited at the anode, until its accumula- 

 tion increases the resistance of the circuit and checks the current 

 and hence the electrolysis which produces the structure. Simi- 

 larly in the case of a regeneration-process where proliferation 

 starts at a cut surface at which previously quiescent cells have 

 been exposed, it is possible that the condition of quiescence is 

 due to insulation by the surrounding cells and other tissue- 

 elements; if these are removed the flow of an electrical current 

 and the formation of new structure are enabled to take place. 



The case of morphallaxis is more complex, and is difficult to 

 simulate by a model of the above kind. In this case constructive 

 processes at one area are accompanied by regressive processes 

 at another area; i. e., growth at one region forms the condition 

 of inhibition of growth or of positive regression at other regions; 

 the whole mass of organized living material is thus worked over or 

 reconstituted until a second equilibrium is reached; the char- 

 acter and distribution of structural material is then similar to 

 that existing before mutilation took place. The conditioning of 

 inhibitory processes at one region by active processes at another, 

 and vice versa, is a frequent phenomenon in organisms; and 

 analogies are afforded by the experiments cited in the preceding 

 section. In general, in any electrolytic couple the processes at 

 the anode are of an oxidative, those at the cathode of a reducing 

 nature; and it is not difficult to understand how in a living organ- 

 ism increased chemical activity of a certain kind at one region 

 (e. g., oxidation) should result in decreased activity (or activity 

 of the reverse type) at another region related to the first in the 

 manner in which the electrodes of a circuit are related to each 

 other. The inhibition of filament-formation at iron surfaces 

 by the contact of a baser metal illustrates an essentially similar 

 condition. The constant form-relations of an organism or of its 

 parts may thus represent a condition where a complex system 

 or combination of electrolytic processes, interrelated as above, 

 mutually equilibrate one another, such equilibration involving 

 a certain constancy in the relative positions, dimensions, and 

 form-characters of the chief structural elements. This condition 

 would imply a constancy in both the morphological and the 



