12 



Absorption of Liquids by Animal Tissues 



absorption, must be mentioned certain conditions peculiar to the muscle which play a 

 minor role in "the phenomena : (1) difference in size (surface) of the muscles used may 

 cause some variation in the average of absorption from any solution, inasmuch as 

 adsorption phenomena are dependent on extent of surface. We should therefore 

 expect to get more marked changes in muscles having surfaces relatively large as 

 compared with the total mass of the muscle; (2) previous activity of the muscle 

 may also vitiate the results, as in the active muscle certain metabolic products 

 are formed (doubtless by enzymic activity), which may increase the osmotic pressure 

 of the muscle-plasma; (3) a third variation is sure to creep in, owing to seasonal 

 differences in the constitution of the frog's blood and tissues. This seasonal varia- 

 tion is shown in the following data of absorption from solutions isosmotic with im 

 NaCl: 



TABLE III 



In considering the results obtained in the absorption from cane-sugar solutions, 

 we must take heed, therefore, of the concentration of the solution as well as its time of 

 action. The chief question at issue, however, is whether we are dealing with a process 

 explicable by the laws of osmotic pressure, or whether this process is due to some other 

 physical or chemical change. From the above table of absorption from cane-sugar 

 solutions, it will be noted that a muscle immersed in a hypertonic solution loses 53 

 per cent, of its weight in twenty-four hours, while in an isosmotic solution it gains 10 

 per cent,, and in a hypotonic solution it gains 87 per cent. This cycle of absorption is 

 exactly that which we should expect providing osmotic pressure effects were prominent. 

 If a solution of salts be separated from a sugar solution by a membrane slowly per- 

 meable to the salts, quickly permeable to the water, and impermeable to the sugar, we 

 should observe that water will pass from the salt solution into the sugar solution, pro- 

 viding the concentration of the sugar solution be greater than that of the salt solution. 

 If the former be equal to or less than the latter, water will pass, to a less or great 

 degree, from the sugar solution into the salt solution. This process is observed in 

 phenomena of absorption from cane-sugar solutions. 



As will be shown later, the sarcolemma of the muscle is slowly permeable to the 

 ions of the salts within the muscle. Along with the passage of water from or into 

 the muscle we will have, therefore, the passage of ions from the muscle into the sugar 



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