116 THE THEORY OF IONS 



tion in which the synthesis has the upper hand by 

 day and the analysis by night."* 



The colloidal constitution of living matter is inti- 

 mately connected with the most important problems 

 of biological chemistry. Chemical reactions of the 

 most different character are simultaneously possible 

 in the colloidal ground substance of the cell. An- 

 tagonistic reactions such as oxidation and reduction, 

 hydration and dehydration, condensation and poly- 

 merisation, synthesis and analysis, go on almost side 

 by side. " Just as the chemist allows different 

 chemical reactions to take place in different vessels, 

 the cell is believed to utilise the different chambers 

 of its honeycomb structure, and, with the aid of 

 colloidal ferments, allows the necessary reactions to 

 go on independently of each other, "f The laws of 

 colloid chemistry govern the changes that go on in 

 the cells, but these laws are modified by the pro- 

 cesses of metabolism and their variations are not 

 clearly understood. In the cells the colloids are 

 more or less jelly-like or in the condition of gels ; 

 but in the tissue juices they are in the fluid condi- 

 tion and are called sols. 



In intra-cellular substances there is a certain 

 parallelism between the changes in colloids and the 

 cellular manifestations, such as in swelling, absorp- 

 tion, movement, and the effects of various stimuli. 

 But the extra-cellular substances of living organisms 

 are subject to direct control by the laws of colloidal 

 chemistry, as investigations have shown. A study 

 of the phenomena exhibited by extra-cellular col- 



* Pauli's " Physical Chemistry in the Service of Medicine," 

 p. 64. t Loc. cit., p. 58. 



