6 Absorption op Liquids by Animal Tissues 



site electric charges are removed together, because the electric charges of the ions hin- 

 der the free movement from the solution. Therefore, if a semi-permeable membrane 

 is impermeable to one ion of a molecule it is impermeable to the other, for, if this were 

 not true, a separation of positive or negative electricity would take place. 



In solutions, therefore, of any of these substances to which the corpuscular mem- 

 brane is impermeable, phenomena of swelling or of shrinking occur if the osmotic pres- 

 sure of the outside solution be less, or more, than that of the solution within this mem- 

 brane. This osmotic value of the solution within the corpuscular membrane varies, 

 according to Hamburger, between that of a .75 per cent. NaCl solution and that of a .9 

 per cent. NaCl solution. 



If, now, we place the corpuscles in solutions of substances to which they are per- 

 meable, osmotic pressure effects play no rCle whatever, even though the concentration 

 of the outside solution be of higher, equal, or lower value than that inside the mem- 

 brane. We find that, in these latter cases, phenomena of swelling or shrinking do not 

 occur. As Hedin points out, the blood corpuscles do not, under such circumstances, 

 obey the laws of osmotic pressure, and, as a result, they give up their haemoglobin to 

 the outside solution. 



Hamburger, in his earlier experiments, had attempted to apply a method based upon 

 that of De Vries's classic work on plasmolysis in plants. He used, in these experiments, 

 the point at which the corpuscle began to lose its haemoglobin as his isosmotic point. 

 He maintained that the corpuscles were, to a high degree, permeable to the salts in 

 question. As a result of this, he says, an equilibrium is established between the 

 osmotic pressure on each side of the membrane. These ideas are, as shown above, 

 totally at variance with the theory of osmotic pressure as advanced by van't Hoff. 



In his work Oker-Blom advanced the idea that entirely erroneous conceptions of 

 the osmotic equivalents of the corpuscles must creep in by use of solutions of salts in 

 water. He advocates the use of solutions in serum, inasmuch as the variation intro- 

 duced in osmotic pressure is, then, referable to the salt added, without considering the 

 consequent lowering of the concentration of the blood on addition of a watery solution 

 of the salt. He shows that, in previous work along these lines, there has always been 

 a question of reciprocal action between the substances present in the animal cells and 

 those with which the cells are brought into contact. In view of such conditions, he 

 says, only the total osmotic pressure of the fluids under observation has been consid- 

 ered, while, from his work, it seems quite evident that the entrance of a substance 

 into a red blood-corpuscle is, clearly, under the influence of the partial osmotic pres- 

 sure of the substance added, inasmuch as no great increase in total osmotic pressure 

 has been caused by this addition. 



My own experiments, few in number, were planned simply with the idea of show- 

 ing, if possible, that we are dealing, in the case of the red corpuscle, with osmotic 

 pressure effects to a large extent. These experiments have no claim to originality, but 

 are confirmatory of the work previously mentioned. The method followed in this 

 work is a slight modification of Hedin' s and Koeppe's hsematokrit method. Mixtures 



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