450 Watcr Absorption by Protoplasm [Mar. 



the formation of new colloidal Compounds when tissue colloids are 

 treated with acids, bases and salts. Even the union between a col- 

 loid and its solvent may be chemical. We do not yet know what 

 is the essential nature of hydration, or to express it more generally, 

 of solvation in Solution. 



Fischer refers to CO2 as one of the factors in the production of 

 edema but does not show why the large quantities of CO, which are 

 normally produced in tissues fail to induce water accumulation in 

 them. (Page 307.) 



The carbonic acid concentration in our body cells and tissues is 

 fairly constant. The colloids take up all the water they can hold 

 under these conditions (normal water content). If we permit the 

 carbonic acid content to run up, as through suffocation, atropin 

 or an anesthetic, the animal does become edematous provided we 

 give him water. If we reduce its carbonic acid content, as by 

 accelerating its heart beat and respiration, by giving caffeine, nico- 

 tin or small doses of alcohol, then we reduce the amount of water 

 that its body colloids can hold and so we get " free " water that 

 leaves the body as an increased urinary flow, increased sweat, etc. 

 See my remarks on secretion in my volume on edema and the 

 various papers I have written since. 



Does the intracellular CO2 have any effect directly or indirectly on 

 the power of lactic acid to cause edema? (Page 307.) 



The two acids act additively. But in the body the production 

 of a stronger acid like lactic will drive off the weaker carbonic acid 

 (acapnia). The ultimate effect on swelling is the algebraic sum of 

 the two in which the nature of the individual acids concerned plays 

 an important part. See the available studies on the effect of differ- 

 ent acids on the absorption of water by protein colloids. 



The experimental procedure in Fischer's work is not always the 

 best that might have been adopted. Fischer's experiments were per- 

 formed with dry masses, and with solid parts of organisms. How his 

 theory could be experimentally verified with blood serum or tissue 

 Juice (dissolved colloids) in the absence of "membranes" or "parti- 

 tions " is not suggested. How do dissolved colloids, as compared with 

 solid colloids, behave in the presence of lactic acid, and phosphates, and 



