ElfDOSMOSE. 9 



and endosmosic action may the tranference be going on from particle 

 to particle, throngli the whole tissue of the bladder, without the 

 formation of any distinct currents of the two fluids as they exist. 



It may be mentioned that the efiect would be similar if the pure 

 water were put into the bladder, and the solution of salt or sugar 

 into the basin in which the bladder is immersed ; but in this case, in 

 accordance with what has been stated, the exosmose would be in 

 excess of the endosmose, more water would be withdrawn than would 

 be replaced. The difierence in the quantity passed by endosmose 

 and exosmose may in both cases be attributed to the difference 

 between the force of the chemical affinity of the saline solution, or 

 the salt in it, for water, and the force of the attraction of adhesion, by 

 which the water is kept attached to the bladder, being greater than 

 the difference between the force of the chemical affinity of the pure 

 water for the Valine solution, and the attraction of adhesion by which 

 that solution .is attached to the bladder. 



If the chemical affinity of the saline solution for water be equivalent 

 to 8, and the attraction of adhesion of this solution to the bladder be 

 equivalent to 6, the difference between these is 2. If the adhesion of 

 water to the bladder be equivalent to 1, and the chemical affinity of 

 the pure water for the salt in the solution be equivalent to 1, the 

 difference between these is 1 ; and the endosmose would be to the 

 exosmose as 2 is to 1. 



Dr Asa Gray, Professor of Natural History in Harvard University, 

 Cambridge, Massachusets, in writing of endosmose and exosmose with 

 a solution of sugar as the subject of experiment remarks, in 

 accordance with what I have stated, — " At the same time, the water 

 in the vessel will become slightly sweet; showing that a small 

 quantity of syrup has passed through the pores of the membrane into 

 the water without, while a much larger portion of water has entered. 

 The water will continue to enter, and a small portion of syrup to 

 leave it, until the solution is reduced to the same strength as the 

 liquid without. If a solution of gum salt, or any other substance, be 

 employed instead of sugar the same result will take place. If the 

 same solution be employed both in the vessel and in the [bladder] 

 no transference or change will be observed. But if either be stronger 

 than the other a circulation will be established, and the stronger 

 solution will increase in quantity until the two obtain the same 

 density. If two different solutions be employed, as, for iustance, 



