NATURE OF DISEASE. 133 



enzymes, etc., that the hyphae inside the cells are 

 enabled to make use of the starch, proteids, etc., 

 they find there. 



All living cells form materials, resulting from the 

 activity of the protoplasm, which we may compare 

 with the refuse or by-products formed in any 

 great manufacturing industry : these by-products 

 have to be got rid of if they are injurious or 

 noisome (excretions), and if not i.e. if they are 

 capable of further use (secretions) they have to 

 be stored away till required. Some of the most 

 prominent of these bodies excreted by fungi are, 

 as w^e have seen, poisonous acids, such as oxalic 

 acid, enzymes, and organic poisons, such as those 

 in ergot. But similar enzymes, acids, poisons, 

 etc., to those found in fungi are also found in 

 the cells of other plants and animals ; for only 

 by means of their solvent actions can processes 

 like digestion and assimilation of the starchy 

 and other materials into the body-substance be 

 accomplished, and we have seen that it is a 

 general property of living cells to form acids, 

 and other excretions and secretions. 



Now we know very little about what may 

 happen when an organism say a fungus 

 secreting especially one kind of enzyme or poison 

 or other active substance, comes into intimate 

 contact with another ^say a leaf-cell which 

 secretes predominantly others, but what we do 

 know points to the certainty that various com- 

 plications will occur. 



For instance, if certain bacteria which prefer an 



