Absorption of Liquids by Animal Tissues 



to the electric nature of the element). This conception of Arrhenius gave the new idea 

 that the dissociation was due to the mere dissolving of the electrolyte in the water, and 

 not, as Clausius had claimed, to the action of the electric current. This electrolytic 

 dissociation of substances in watery solution is by no means complete at every concen- 

 tration, but increases with the dilution until, at infinity dilution, a complete dissocia- 

 tion of the molecules into their respective ions takes place. We have, therefore, in a 

 watery solution of an electrolyte two kinds of molecules — the active (electrically dis- 

 sociated), and the inactive (non-dissociated). Inasmuch as the ions of the dissociated 

 molecules each exert pressure, we may readily understand how the osmotic pressure of a 

 substance in watery solution will show a much higher value as the degree of dissoci- 

 ation becomes greater. 



The bearing of the theory of osmotic pressure upon phenomena of absorption is 

 easily seen to be of the first magnitude. If a substance in watery solution be sepa- 

 rated from the pure solvent by a membrane permeable to the solvent, but not to the 

 solute, we have the conditions necessary for the solving of problems of osmosis. In such 

 a case, as van't Hoff showed, water will pass into the solution, and, after a time, will 

 establish a condition of equilibrium due to the pressure of the water which enters in 

 minimal quantities. Of course the water, under such circumstances, does not give rise 

 to the osmotic pressure measurable by a manometer, inasmuch as it is present on both 

 sides of a membrane permeable to it. The pressure is, in this case, due solely to the 

 dissolved particles, and may be explained by the kinetic theory, or the water-attraction 

 of the parts dissolved. 



If, instead of a membrane strictly impermeable to the dissolved particles, we have 

 one which allows the passage of some, at least, of the dissolved particles we have a 

 slightly different condition of affairs. In such a case the osmotic pressure w^ill be a 

 minimum and the process will resolve itself into one of diffusion, as the membrane 

 being permeable to the solvent and solute, will not in any way hinder the diffusion pro- 

 cess. However, if we add to such a condition the further complexity of two solutions 

 separated by a membrane, freely permeable to the solvent and difiicultly so for the 

 solute, we have the conditions as they exist in the various cells of the body. 



Experiments on absorption of liquids, or, in other words, upon processes involved 

 when the conditions stated above exist, have been made on organized as well as unor- 

 ganized material. The tissues chiefly involved in such work have been red-blood cor- 

 puscles, muscles, and intestines ; while the unorganized material has been that known 

 under the general name of colloid matter, including, here, gelatine, albumin, sodium- 

 oleate, silicon-dioxide, etc. In the present work I have confined myself chiefly to the 

 effects of solutions of various electrolytes and non-electrolytes upon absorption by mus- 

 cular tissue. However, a few introductory experiments upon red blood-corpuscles 

 were made, as it had been shown by various workers that absorption by these cells obeys 

 the laws of osmotic pressure to a large extent, while my results on muscular tissue seem 

 to show that variations in osmotic pressure cannot account, entirely, for phenomena 

 noted in the latter case. 



106 



