Ralph W. Webster 



11 



muscle-plasma) upon one side of a membrane partially permeable (as will be shown 

 later) to these salts, and, on the other side of this membrane, pure water to which the 

 membrane is more or less freely permeable, is a rapid passage of water into the salt 

 solution and a very slow passage of ions into the water. As the time of the experi- 

 ment is extended, we find that a point is reached when the outside concentration of 

 salt may be greater than that inside. In consequence of this condition water passes 

 from the muscle into the solution. Possibly the osmotic pressure within the muscle 

 may be increased by the production of sarco-lactic acid, in which case the steady 

 increase in absorption may be accounted for. Hof meister states that a muscle immersed 

 in water absorbs a certain amount, which cannot exceed a limit known as the "maxi- 

 mum of swelling," which limit is dependent on the amount of (1) capillary imbibition, 

 (2) osmosis, and (3) adsorption. Our results show that a large part of the absorption 

 from water is due to direct endosmotic imbibition. 



6. Absorption from Cane Sugar Solutions. — The absorption noted when a 

 muscle is placed in solutions of various concentrations of cane sugar is as follows : 



TABLE II 



It is quite evident from the above table that the absorption is dependent on 

 certain main factors, viz.: (1) time of action of the solution, (2) concentration of the 

 solution, (3) nature of the substance in solution. It will be observed that the effects 

 during the first hour are much more marked, relatively speaking, than during the 

 other intervals. As will be shown later, the effects are not purely those due to the 

 differences in osmotic pressure on both sides of the sarcolemma, but are, rather, espe- 

 cially in the case of salts, a mixture of osmotic and specific molecular or ionic effects, 

 together with effects due to metabolic changes. It may, however, be said here, that 

 in the earlier intervals osmotic pressure effects are much the more prominent. 



The effect of concentration of the solution may also be noted in the above table. 

 It appears to be a general rule that hyper-tonic solutions bring about a negative absorp- 

 tion during the first intervals, while the iso- and hypo-tonic solutions cause a positive 

 absorption. This negative absorption of the first few hours may or may not change 

 in the later intervals to a positive one, according to the nature of the substance in 

 solution. 



Along with these factors which influence the action of solutions in phenomena of 



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