August 24, 1917] 



SCIENCE 



191 



in its turn by an equivalent of sodium hy- 

 droxid, the amount of water absorbed gradu- 

 ally increases in the form of the right arm of 

 the letter U. Swelling is least in the pure so- 

 dium bicarbonate, increases slowly in the so- 

 dium carbonate and then more rapidly as this 

 is replaced by sodium hydroxid. The swelling 

 of gelatin in pure sodium bicarbonate is 

 slightly higher, in the concentration employed 

 by us, than in pure water. 



Practically the same findings as have been 

 detailed for gelatin in the paragraphs given 

 above were encountered when the swelling of 

 fibrin was studied in different concentrations 

 of the pure salts or in mixtures of these, vary- 

 ing between the extremes of acid on the one 

 hand and alkali on the other. 



It has been iwinted out in previous papers' 

 that the swelling of a protein and its lique- 

 faction or " solution " are totally different 

 processes. The " solution " of gelatin is, in 

 other words, not merely the extreme or a con- 

 tinuation of the swelling of a protein. We 

 were able to verify these results in studying, 

 in parallel with the swelling of gelatin in poly- 

 basic acids and their salts, its " solution " un- 

 der the same circumstances. 



When gelatin containing a unit amount of 

 water, and solid at ordinary room tempera- 

 ture, has mixed with it phosphoric acid, phos- 

 phate mixtures or sodium hydroxid in the 

 concentrations already discussed above, it is 

 found that the " solution " or liquefaction of 

 the gelatin parallels its swelling. In other 

 words, gelatin remains solid in phosphate mix- 

 tures of various kinds, but tends to lose in 

 viscosity, to liquefy and to remain fluid as we 

 pass from the phosphates in the direction 

 either toward acid or toward alkali. 



We hold these experiments to be corrobora- 

 tive of, and to bear uiwn notions previously 



1 Martin H. Fischer, Science, N. S., Vol. XLII., 

 p. 223 (1915) ; KoUoid Zeitschr., Vol. XYll., p. 1 

 (1915). 



expressed regarding the importance of acids, 

 of alkalies, of various salts and of these in 

 mixture in determining the amount of water 

 absorbed by protoplasm under physiological 

 and pathological conditions. The well-estab- 

 lished qualitative and quantitative analogy 

 between the absorption of water by various 

 hydrophilic colloids (like the proteins) and 

 isolated cells, organs or organisms, whether of 

 animal or vegetable origin, shows that proto- 

 plasmic water absorption is essentially a 

 colloid-chemical phenomenon. These studies 

 with polybasic acids and their salts therefore 

 bring further proof of the importance of an 

 abnormal production or accumulation of acids 

 within such colloid systems for increasing the 

 amount of water thus held, and so of explain- 

 ing the mechanism by which the abnormally 

 high hydrations of living cells are brought 

 about as observed in edema, excessive turgor 

 and plasmoptysis, or in those various " dis- 

 eases " which are in essence only edemas of 

 the involved organs like nephritis, glaucoma 

 and " uremia." These experiments also show 

 how coincident with, but not synonymous with 

 the increased swelling there also occur a " soft- 

 ening " - and an increased " solution " of the 

 colloids of the involved tissues, thus explain- 

 ing further the " softening " of organs after 

 an initial swelling together with the appear- 

 ance of increased amounts of colloid (like pro- 

 tein) in the fluids bathing or expressed from 

 the involved edematous tissues (albuminuria, 

 excessive protein content of spinal fluid in ede- 

 mas of the central nervous system, increased 

 protein content of serous accumulations, etc.). 

 Martin H. Fischer, 

 Marian 0. Hooker, 



M^iRTIN BeNZINGER, 



Ward D. Coffman 

 EiCHBERG Laboratory of Physiology, 

 Ukiversitt of Cincinnati, 

 May 30, 1917 



= For a diseussion of tissue softening as due to 

 the breaking of an emulsion see Martin H. 

 Fischer and Marian 0. Hooker, Science, N. S., 

 Vol. XLIII, p. 468 (1916) ; "Fats and Fatty De- 

 generation," 76, New York, 1917. 



