ELECTRICALLY CHARGED MOLECULES. 79 



particles have a negative charge can be caused to coagulate (go into 

 the gel stage) by one of two means: either by positively charged ions, 

 or by the positive electrode of a battery. The coagulating effect of ions 

 increases with their valency, and much more rapidly than the valency. 

 The most valuable among Hardy's discoveries is the fact that in a solu- 

 tion of white of egg the colloidal particles can be rendered either posi- 

 tively or negatively electric by the addition of hydrogen or hydroxyl 

 ions. When the neutral or isoelectric point is reached, the slightest 

 change — one feels almost inclined to use the word 'stimulus' — is suffi- 

 cient to transform the solution into a gel. 



But long before the critical point of a colloidal solution is reached 

 the variation in the charge of the colloidal particles alters their phys- 

 ical properties. An increase in their charge has the same effect as if 

 the viscosity of the liquid were increased. 



The bulk of our protoplasm consists of colloidal material, and the 

 physical manifestations of life, such as muscular contractions and pro- 

 toplasmic motions, and the innervations, are due to changes of the 

 condition of these colloidal solutions. We now may be able to under- 

 stand why the electrical current is the universal form of stimulation. 

 The reason may be that the particles in colloidal solutions are elec- 

 trically charged, and that every alteration of the charge of the par- 

 ticles will result in a process of innervation or a contraction or 

 protoplasmic motion, etc. We likewise understand why the ions, on 

 account of their electrical charges, are equally well capable of alter- 

 ing the physiological properties of the tissues, as the galvanic current. 



But how can the ions cause toxic and antitoxic effects through 

 their electrical charges? In my preliminary notice on these experi- 

 ments which appeared in Pfliigers Archiv in November, 1901, I 

 pointed out the possible relation of the electrical charges to the vis- 

 cosity of the protoplasm. Phenomena of cell division are, as I believe 

 with Biitschli and Quincke, phenomena of protoplasmic streaming. 

 Such phenomena require, as Quincke has shown, a definite degree of 

 viscosity. If the viscosity is too great, no protoplasmic motion is 

 possible, and the same is true if the viscosity is too small. It may be 

 possible that the toxic charges — presumably the negative one in the 

 case of sodium salts — alter the viscosity of the protoplasm by either 

 making it too liquid or too viscous, thus preventing the protoplasmic 

 motions necessary for cell division or the muscular contraction. Small 

 quantities of oppositely charged ions with a higher valency, which give 

 off their charge sufficiently readily, will act as antitoxic substances. 



2. The thermodynamical theory of life phenomena has utterly failed 

 to show how the thermal energy produced through the splitting up and 

 oxidation of foodstuffs can lead to muscular contraction. Engelmann's 

 well-known attempt at an explanation is based on a physical impossi- 



