488 ROBERT CHAMBERS, JR. 



being probably more viscous than the external. They are not 

 readily coagulated with salts, their two phases can be separated 

 only with considerable difficulty and they possess the peculiar 

 property of existing in liquid or in solid or pectinized states, 

 either one of which is capable of being transformed into the 

 other. The liquid state is called a sol and the solid state a gel. 

 The ability of passing one into the other is spoken of as a rever- 

 sible action. In the sol the internal phase is in a highly dispersed 

 condition. In the gel the degree of dispersity of the internal 

 phase is decreased to a minimum until in all probability the dis- 

 persed phase passes into a continuous phase (Hatschek, '16, p. 63), 

 the two phases of the colloid becoming, so to speak, locked one 

 in the meshes of the other.^ 



In protoplasm we meet with properties which are peculiar to 

 solutions of colloids of the emulsoid class, ^ having water as the 

 basis of its dispersion-medium. It is more viscous than a true 

 solution, water diffuses through it with readiness (Chambers, 

 '17), and it is capable of forming reversible sols and gels (see 

 this paper, experimental parts). 



Biitschli based his theory of the alveolar structure of proto- 

 plasm on a comparison of protoplasm with experimentally pro- 

 duced foam structures. He observed the striking similarity be- 

 tween the microscopic picture of a finely divided emulsion of 

 xylol in a soap solution and a protoplasmic network. He also 

 pointed out that variations in the viscosity of protoplasm could 

 be explained by such an emulsion structure.^ Optically homo- 

 geneous protoplasm he interpreted as possessing alveoli the walls 



^ This process may continue until a complete reversal of the phases takes 

 place, the originally internal phase becoming the external phase and vice versa. 

 The internal phase of an emulsion-colloid or emulsoid being more viscous than 

 the external phase (which is aqueous), a reversal of the phases produces a solidi- 

 fying of the diphasic system. 



^ It is significant that the vast majority of organic emulsion-colloids are 

 hydrophilic. 



^ An emulsion of oil droplets in a soap solution is liquid when the oil exists in 

 a comparatively low degree of dispersity. On sufficient shaking the dispersity 

 of the oil is raised and the surface of contact between the emulsified oil and the 

 emulsion's medium is so enormously increased that the resulting surface tension 

 solidifies the mass. 



