Royal Society, 155 



The osmotic action of carbonate of potash and other alkaline salts 

 is interfered with in an extraordinary manner by the presence of 

 chloride of sodium, being reduced almost to nothing by an equal 

 proportion of that salt. The moderate positive osmose of sulphate 

 of potash is converted into a very sensible negative osmose by the 

 presence of the merest trace of a strong acid, while the positive 

 osmose of the first-mentioned salt is singularly promoted by a small 

 proportion of an alkaline carbonate. The last statement is illustrated 

 by the following observations : — 



Osmose in same membrane. 



Degrees. 



1 per cent, sulphate of potash 21 



Same 4-0*1 per c. carb. potash . , 254 



Same + Same 264 



0*1 per cent, carbonate of potash alone 92 



Same 95 



It may appear to some that the chemical character which has 

 been assigned to osmose takes away from the physiological interest 

 of the subject, in so far as the decomposition of the membrane may 

 appear to them to be incompatible with vital conditions, and that 

 osmotic movement must therefore be confined to dead matter. But 

 such apprehensions are, it is believed, groundless, or at all events pre- 

 mature. All parts of living structures are allowed to be in a state 

 of incessant change, of decomposition and renewal. The decompo- 

 sition occurring in a living membrane, while effecting osmotic pro- 

 pulsion, may possibly therefore be of a reparable kind. In other re- 

 spects chemical osmose appears to be an agency particularly adapted 

 to take part in the animal oeconomy. It is seen that osmose is pecu- 

 liarly excited by dilute saline solutions, such as the animal juices 

 really are, and that the alkaline or acid property which these juices 

 always possess is another most favourable condition for their action 

 on membrane. The natural excitation of osmose in the substance 

 of the membranes or cell- walls dividing such solutions seems there- 

 fore almost inevitable. 



In osmose there is further a remarkably direct substitution of one 

 of the great forces of nature by its equivalent in another force — the 

 conversion, as it may be said, of chemical affinity into mechanical 

 power. Now what is more wanted in the theory of animal functions 

 than a mechanism for obtaining motive power from chemical decom- 

 position as it occurs in the tissues ? In minute microscopic cells, the 

 osmotic movements should attain the highest velocity, being entirely 

 dependent upon extent of surface. May it not be hoped, therefore, 

 to find in the osmotic injection of fluids the deficient link, which 

 certainly intervenes between muscular movement and chemical de- 

 composition ? 



