20 THE HUMAN BODY 



salt is evenly distributed throughout the solvent there will be 

 dialysis of both substances until an even distribution is obtained. 



Again, both osmosis and dialysis bring about changes in the 

 concentration of the solutions affected by them whereas filtration 

 does not. In considering the influence of the membranes of the 

 Body upon its liquid contents these facts must be borne in mind. 



Summary. We may summarize the physico-chemical structure 

 of living tissues by picturing them as made up of a large percentage 

 of colloids and a small percentage of crystalloids dissolved in a 

 relatively considerable amount of water, and subdivided into 

 units each of which is enclosed in a membrane. Among the units 

 (cells) are spaces filled with a watery fluid (lymph). Interchanges 

 between cell substance and lymph take place through the cell 

 membranes in the main in accordance with the laws of filtration, 

 osmosis, and dialysis. 



