191 1] William J. Gies * 291 



Turgor, plasmolysis and plasmoptysis. Turgor, plasmolysis 

 and plasmoptysis are discussed by Fischer from the Standpoint of 

 his experimental observations on water absorption by colloids (pp. 

 156-180). 



It is impossible to escape the experimentally well grounded conclu- 

 sion that most, if not all, cells do not follow the laws of osmotic pres- 

 sure. The attempts that have been made to harmonize the observed 

 behavior of various cells with that demanded on the theory that cells 

 represent osmotic Systems are ingenious, but we can scarcely believe 

 sufificiently supported by experiment to be convincing. For the most 

 part the explanations given are complicated, which constitutes in itself 

 a threatening feature when the explanation of any natural phenomenon 

 is hazarded. What strikes one as particularly encouraging about the 

 colloidal idea of water absorption is its simplicity, and the breadth of 

 water absorption phenomena to which it may be applied without appar- 

 ent experimental or theoretical objection. (Page 158.) 



The absorption of water by kidney and liver cells is essentially a 

 function of their colloidal State. What was said regarding these cells 

 is also true regarding the behavior of spermatozoa, of white blood cor- 

 puscles and of the epithelial cells of the bronchi, intestine, bladder and 

 esophagus. (Page 158.) 



All the cells mentioned in this paragraph swell less in any salt Solu- 

 tion than in distilled water. With every increase in the concentration 

 of the salt there comes a progressive decrease in the amount of the 

 swelling. At a certain concentration the cells maintain for a variable 

 length of time what is considered their " normal " volume. If the concen- 

 tration is increased beyond this they shrink. In this brief description 

 are exemplified all that is contained in the terms plasmoptysis, turgor, 

 and plasmolysis as understood by the plant physiologists. Impossible 

 as it is to understand all these phenomena on the basis of osmotic pres- 

 sure, equally easy is it to see in them a perfect parallel of an emulsion 

 colloid swelling in a dilute acid in the presence of variable amounts of 

 any salt. (Page 159.) 



If a frog's muscle is dropped into distilled water it suffers a progres- 

 sive increase in weight. This phenomenon is usually interpreted as a 

 response to immersion in a Solution of too low an osmotic pressure, so 

 that water is absorbed by the cell Contents. I maintain that this is not 

 correct, for were it, all our muscles ought to swell whenever we con- 



