78 POPULAR SCIENCE MONTHLY. 



In the meantime I had become familiar with the brilliant experi- 

 ments of Hardy upon the influence of ions and the galvanic current 

 upon colloidal solutions. They indicated to me that the next step I 

 had to take was to see whether or not the valency and the sign of the 

 electrical charge of an ion determine its physiological effects. I sus- 

 pected that the antitoxic effect of the calcium ion in the above-men- 

 tioned experiment was due to its electrical charge and decided to 

 investigate in a more systematic way whether or not the sign and 

 quantity of the electrical charge influence life phenomena. My experi- 

 ments carried on at Woods Hole this summer showed conclusively that 

 this is the case for the antitoxic effects of ions and probably for the pro- 

 duction of rhythmical contractions through ions. It seems at least pos- 

 sible that it is true also for artificial parthenogenesis. 



Theoretical Considerations. 



1. We have to attempt to answer the question, How can the electri- 

 cal charges of ions produce a toxic or antitoxic effect? The answer 

 to this question must be preceded by the answer to the more general 

 question, How can the electrical charges of ions as well as of an 

 electric current influence life phenomena? The basis for the answer 

 to this question will undoubtedly be found in the work of Hardy, as 

 well as that of Bredig, on the role of the electrical charges of the 

 particles in a colloidal solution. Hardy has shown that living pro- 

 toplasm is to be considered as a colloidal solution, a hydrosol. Such 

 hydrosols are suspensions of solid particles in a fluid (water). These 

 particles are at the highest about 1,000 to 10,000 times as large as the 

 dimension which the kinetic theory of gases assumes for the molecules. 

 The forces which keep these particles in solution are of an electrical 

 nature. There exists, according to Helmholtz and Quincke, a double 

 electrical layer at the limit between particle and surrounding water. 



When the colloidal particles have a positive charge, the surround- 

 ing particles of the water have an equal negative charge. It agrees 

 with this assumption that the colloidal particles move under the in- 

 fluence of an electrical current in the same way as ions. They move 

 to the anode when they carry a negative charge, and to the kathode 

 when they carry a positive charge. Hardy has made it probable that 

 these charges keep the particles in solution, inasmuch as through these 

 charges they must repel each other. Hardy has shown that as soon 

 as these charges are taken away from them the colloidal particles will 

 no longer be held in suspension, but either fall down or rise to the 

 surface. In this case the hydrosol is transformed into a hydrogel. 

 These charges can either be taken away from them through the oppo- 

 sitely charged electrode of a battery, or through oppositely charged 

 ions which easily give off their charge. Solutions whose colloidal 



