OFMOTIC I'fx'ESSrUE 33 



])}' ])rodnc'ino- from proteins that liave no osmotic pressure erystal- 

 !t)i(lal substances tluit do luive osmotie pressure, cause intracellular 

 osmotic conditions to be continually varjdng. As a result, streams 

 of diffusin<>- particles arc m()vin<«- a])out in every direction, settinjr up 

 new chemical reactions and consequent new osmotic currents. The 

 {2:reater the ditlt'erence in osmotic pressure between a cell and its 

 environs, and between the ditferent parts of the same cell, the more 

 powerful the osmotic efiPects, and as a result the g^reater the capacity 

 for accomplish inji' work. The storing- up of insoluble and inditfusiblc 

 forms of substance, such as glycogen, fat, and proteins, is an im- 

 portant factor in maintaining inequalities in osmotic pressure, and 

 in this way of increasing work Capacity. 



Indeed, we may look upon cell life as a constant attempt at the 

 esta])lishment of equilibrium, both chemical and osmotic, which is 

 never achieved because the move towards one sort of equilibrium is 

 always against the other. All the food-stut?s — fats, carbohydrates 

 and proteins— are characterized by being colloids when intact and 

 crystalloids when disintegrated, thus: 



colloidal proteins ?^ crystalloid amino acids 

 colloidal o'lycQcren 5=^ crystalloid sugar 

 nondiffusihlo fats ^ diffusible soaps and glycerol. 



In consequence of this, if the crystalloids dififuse from the blood into 

 a cell there is at once an excess of this end of the equation, and, 

 hastened by the intracellular enzjones, partial synthesis to the colloid 

 soon occurs to establish chemical equilibrium. Chemical changes in 

 the crystalloids, by oxidation, reduction or hydrolysis, upset this chem- 

 ical equilibrium, and hence further diffusion, synthesis and hydrolysis 

 continue, one upsetting the other continuously. If equilibrium were 

 established we should have no further reactions, and the cells would 

 be inactive. The constant upsetting of the equilibrium is what con- 

 stitutes cell life. 



The relation of osmotic pressure and osmosis to physiological prob- 

 lems is only beginning to be studied. It is apparent that they must 

 be of essential importance in absorption from the alimentary canal, 

 in absorption and excretion between the cells and the blood stream, 

 and in secretion by glandular organs; but it is also certain that 

 they are no less important in all the less obvious chemical and phys- 

 ical processes of the cell.^'^ In pathological processes osmotic pressure 

 may play an equally important role, and the facts discussed in the 

 preceding paragraphs will be alluded to frequently in subsequent 

 chapters. 



1' For further consideration of the subject of osmotic pressure in these rela- 

 tions see: Livingston, "The Role of Diffusion and Osmotic Pressure in Plants." 

 University of Chicaeo Press, Cliicago. 100.3; Czapek. "Biocheniie der Pflanzen," 

 Jena, lfl03. Also, Spiro, Pauli and Ilobcr, all previously cited. 

 3 



