CELLULAR ORGANIZATION OF LRqNO AT N'l^ri- R -n 



fact that they arc presencd unly while the cell remains 

 living. All cells disintegrate on death; the vital semi- 

 permeability and water-immiscil)ility are then lost. 

 Any living cell, such as a blood cor])uscle, sus])en(ied 

 in its normal medium, exhibits general i)hysical ])n)perties 

 similar to those of a suspended insoluble particle; e.g., an 

 oil drop. These properties are largely an expression of 

 general physical conditions present at all boundary 

 surfaces between adjacent phases, and their consideration 

 becomes of great importance to the physiologist. 



In common with other boundary- surfaces between 

 mutually immiscible phases the cell surfaces have 

 characteristic electrical properties (interfacial potential 

 differences), exhibit surface tension, and possess the 

 property of condensing or absorbing dissolved substances 

 from the surrounding solution (adsorption). The general 

 role of adsorption in protoplasmic activity is a highly 

 important one, to be considered later in more detail; 

 and undoubtedly this process is a chief factor in the 

 catalytic or quasi-catalytic action of living matter. 

 In general, the catalytic properties of linely divided 

 substances, such as charcoal and colloidal metals, arc 

 referable — at least in large part— to adsorption, and the 

 same is probably true of the catalytic properties of living 

 cells. Adsorption appears also to be a factor in the 

 collection of nutrient and other substances from very 

 dilute solution, also a highly characteristic feature of 

 protoplasmic activity. 



These considerations show that in adtlition to limiting 

 diffusion and thus providing for structural and chemical 

 differentiation in the manner indicated, the cellular or 

 partitioned structure of li\ing matter is physiologically 



