354 BACTERIAL POISONS. 



excretions of all living things, plants and animals, contaii) 

 substances which are poisonous to the organisms which 

 excrete them. A man may drink only chemically pure 

 \yater, eat only that fo(5d which is free from all adultera- 

 tions, and breathe nothing but the purest air, 'free from all 

 organic matter, both living and dead, and yet that man's 

 excretions would contain poisons. AVhere do these poisons 

 originate? They are formed within the body. They 

 originate in the metabolic changes by which the complex 

 organic molecule is split up into simpler compounds. We 

 may suppose — ^indeed, we have good reasons for believing — 

 that the proteid molecule has certain lines of cleavage along 

 which it breaks when certain forces are applied, and that 

 the resulting fragments have also lines of cleavage along 

 which they break under certain influences, and so on until 

 the end-products, urea, ammonia, water, and carbon-dioxide 

 are reached ; also that some of these intermediate products 

 are highly poisonous has been abundantly demonstrated. 

 The fact that the hydrocyanic acid molecule is a frequent 

 constituent of the leucomaines is one of great significance. 

 We know that chemical composition is an indication of 

 physiological action, and the intensely poisonous character 

 of some of the leucomaines conforms to this fact. It 

 matters not whether the proteid molecule be broken up by 

 organized ferments, bacteria, or by the unorganized fex*- 

 ments of the digestive juices, by the cells of the liver or by 

 those still unknown agencies, which induce metabolic 

 changes in all the tissues — in all cases poisons may be 

 formed. These poisons will differ in quality and quantity 

 according to the proteid which is acted upon, and according 

 to the force which acts. 



Peptones formed during digestion do not in health reach 

 the general circulation. When injected directly into the 

 blood they act as powerful poisons. They destroy the 

 coagulability of the blood, lower blood-pressure, and in 

 large quantities cause speedy death. Brunton attributes 

 the lassitude, depression, sense of weight in the limbs, and 

 dulness in the head occurring in the well-fed, inactive man, 

 after his meals, to poisoning with peptones. The remedy 



