22 PLANT DISEASE 



that bacteria can only live on foods that 

 correspond more or less with their own chemi- 

 cal composition. 



Another factor is that proteids are fatal to 

 bacteria, and the fact that a normal haemo- 

 globin, which is of the nature of a proteid, is a 

 poison to these, explains why these fungi are 

 never found in a normal blood, for the all- 

 powerful reason that they could not live 

 in it. 



This reduces the whole question again to 

 the fact that a normal haemoglobin, through 

 its various functions, which I have explained 

 in the previous chapter, renders the animal 

 immune to an innumerable number of bac- 

 terial or fungoid diseases, and explains the 

 constant factor spoken of by Reindfleisch. 



In other words, the blood is the life, and 

 variation in its chemical composition simply 

 means variation in the health of the animal. 

 We know it is a common thing for animal 

 life to die of acute anaemia. I shall show 

 later how in anaemia there must be a propor- 

 tionate deficiency of carbohydrates and pro- 

 teids, and that they must vary as the haemo- 

 globin. 



