22 Absokption of Liquids by Animal Tissues 



tions affect the permeability of the muscle for non-ionized substances, such as cane 

 sugar and urea, we are not in a position to state, as no direct experiments were made 

 bearing on the point of outward penetrability of urea. Cane sugar, it will be remem- 

 bered, does not seem to penetrate the sarcolemma at all and therefore obeys perfectly 

 the laws of osmotic pressure. 



II. OSMOTIC PRESSUEE EFFECTS 



a. At the beginning of this section it may be asserted that differences in osmotic 

 pressure, on both sides of the sarcolemma, do not account for the results of absorption 

 of fluid by muscle. Hamburger's work on the red-blood corpuscle apparently proved 

 that such was the case in phenomena noted in his experiments. He, however, 

 neglected the consideration of partial osmotic pressure as well as the question of per- 

 meability of corpuscular membrane to certain ions, in which latter case osmotic 

 pressure could play no r6le whatever. From our own experiments on blood-corpuscles 

 we find, by use of Hedin's haematokrit method, that the corpuscles do, apparently, 

 obey osmotic laws if solutions of K, Na, Ca, etc., salts be used. Yet we cannot assert 

 from these experiments that these laws are the only ones governing the phenomena 

 noted, inasmuch as our work on the muscle shows us, conclusively, that osmotic effects 

 are accountable for slight changes only. 



h. Generally speaking, a muscle immersed for a short interval in a hypertonic 

 solution of an electrolyte or non-electrolyte will lose in weight ; if placed in an isotonic 

 solution it may or may not gain, while in a hypotonic solution of the same substance 

 it regularly increases in weight. Miss Cooke has found, it will be recalled, that in a 

 solution of ^m NaCl (5.1087 atmospheres pressure) a muscle neither gains nor loses 

 in weight in eighteen hours. The assumption was very natural that this NaCl solution 

 was isosmotic with the muscle plasma, as Loeb's previous work showed that the effects 

 of acids and alkalies were proportional to the number of free H and OH ions present 

 in the solutions. This assumption is, however, open to several serious objections. In 

 the first place it has been shown by Pfeffer, Linebarger, Picton and Linder, Sabanejew, 

 Tamman, and others, that colloids have, in solution, slight osmotic pressure values. 

 In the second place, as we have shown above, Na, K, Ca, SO4, CI ions penetrate the 

 sarcolemma in both directions though at a varying rate in each direction. We must, 

 therefore, conclude that the laws of osmotic pressure do not explain the phenomena 

 noted in these absorption experiments. The markedly different effects of isosmotic 

 solutions of various chlorides show us that the ionic effects far exceed the osmotic 

 effect noted in these experiments. 



c. If the question of interchange of ions or molecules through animal membranes 

 be considered, we find that the relative semi-permeability to ions must determine 

 whether or not osmotic pressure laws are valid in such experiments. Our experiments 

 show clearly that we are dealing in this phenomenon of absorption of fluid by muscle 

 with a combination of ionic effects on the one hand with those of osmotic pressure and 

 hydro-diffusion on the other. The laws of diffusion state that substances, obeying 



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