58 PHYSICAL CHEMISTRY IN MEDICINE. 



the liquid producing the swelling in combinations vary- 

 ing from those that are exceedingly loose to those that 

 are very firm. In this way is rendered possible a great 

 diversity in absorption phenomena as well as the formation 

 of solid and liquid solutions. From this metastabile con- 

 dition of equilibrium the gel gradually endeavors to 

 attain one in which all the colloidal particles are swollen 

 to the same degree. In living matter colloidal material 

 is being constantly broken down and built up anew, and 

 in this way the progress toward a final condition of 

 equilibrium in the molecular disposition of the liquid 

 producing the swelling is steadily destroyed. 



IV. 



The colloidal constitution of living matter is intimately 

 connected with one of the most important problems in 

 biological chemistry, i.e., with the question of the spacial 

 differentiation of the chemical reactions in protoplasm. 

 Since colloids resist the diffusion into them of other col- 

 loids, it is self-evident that through the presence of 

 different colloids within a cell as many different localities 

 are provided in which chemical reactions having a more 

 or less different course may take place.* With the 

 exception of these coarser divisions between chemical 

 reactions, physiological experience compels us to believe 

 that chemical reactions of the most different kinds are 

 simultaneously possible in the homogeneous, colloidal 

 ground-substance of the cell. In even the smallest par- 



* The great importance of the differentiation of the cell into nucleus 

 and cell body has been proven beyond question. Reactions that are 

 connected with the heterogeneous constitution of the cell no longer 

 take place when the cell is destroyed mechanically. 



