DIGESTION IN THP] MOUTH 757 



disintegration of the complex molecules making up the granules, 

 we should have a sudden multiplication of molecules within the 

 granules. This would cause a large rise of the osmotic pressure 

 in these granules and the consequent absorption of water from the 

 surrounding protoplasm. This process, however, could only result 

 in the production of a fluid in the granules having the same osmotic 

 pressure as the surrounding medium, whereas we know that saliva 

 has a molecular concentration which is only one half of that of the 

 blood or lymph. We should therefore have to make a second assump- 

 tion, namely, that, before the extrusion of the solution from the 

 granules, there is a further breakdown of the metabolites by a process 

 of oxidation, with the production of carbon dioxide which diffuses 

 into the surrounding protoplasm. We have, however, no evidence 

 of either of these processes or for any of these assumptions, and 

 I have only adduced them in order to show how far we are still from 

 the actual comprehension of the events occurring in every living 

 cell, and underlying its conditions of rest and activity. 



