LIFE AND DEATH. 277 



oxidised are now in part left to form other 

 compounds in the surrounding Hquid, and thus 

 incompletely oxidised bodies, such as vegetable 

 acids, alcohols, etc., accumulate. Even in the 

 complete absence of atmospheric oxygen the 

 protoplasm may go on breaking down and 

 accumulating various compounds containing re- 

 latively much carbon and hydrogen so-called 

 intramolecular respiration ; but in ordinary plants 

 this process soon comes to an end, because the 

 blocking up of the molecular plexus leads to 

 obstruction and interferes with the normal assimi- 

 lation and dis-assimilation, and, if prolonged, leads 

 to pathological conditions, and eventually death. 



Here, then, we meet with a cause of disease, or 

 of predisposition to disease. The deprivation of 

 oxygen interferes with the normal processes of 

 building up and breaking down of the proto- 

 plasmic molecules, and bodies we term poisonous 

 accumulate and may lower the vitality or even 

 bring life to an end. 



During normal life other products of the dis- 

 ruption of the protoplasm molecules are nitrogenous 

 bodies, such as proteids, and these we have reason 

 to believe are used up again, acting as the nuclei, so 

 to speak, of the new molecules, and so being built 

 up again with fresh food -materials into the plexus, 

 to be again set free, and again used up, and so on. 

 Others are the carbohydrates, such as cellulose, 

 which pass out of the molecule into an insoluble 

 form, and are accumulated outside the protoplasm 

 in the form of cellulose membranes, and so forth. 



