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 ceconomy. 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 ? 



II. " Examination of the Cerebro-spinal Fluid." By WILLIAM 

 TURNER, Esq., Scholar of St. Bartholomew's Hospital. Com- 

 municated by JAMES PAGET, F.R.S. Received May 18, 

 1854. 



In the Bulletin de 1'Academie de Me"decine for December 1852, a 

 paper is published by M. Bussy, containing an analysis by M. Des- 



