'746 PROCEEDINGS OF SECTION li. 



strated in numerous diseases, such as anthrax or splenic 

 fever, tuberculosis, tetanus, diphtheria, and others. 



The specific microbe of every infectious disease has not in 

 all instances been yet isolated, but there can be no doubt by 

 analogy that each infectious disease owes its infectivity to 

 the presence of its own special micro-organism, and to none 

 other, for its development. 



As microbes have the power of forming chemical products 

 by their growth and multiplication, as well as by their action 

 upon the tissues with which they may be surrounded, it is 

 probable that where no bacilli are found in the system, as in 

 some diseased states — hydrophobia and tetanus for example — 

 the morbid condition may be due to the action of these 

 chemical products, which are easily absorbed and carried into 

 the tissues of the body by blood vessels and lymphatics. 



In diphtheria the microbes are only found on the mucous 

 membrane at the seat of invasion, and not inside the body 

 generally, and yet this is a very fatal disease, as if the system 

 were poisoned directly by the absorption of the material 

 produced by the microbes. 



It appears, then, that in some cases of disease the chemical 

 products of pathogenic bacilli are apparently the sole agents 

 in the production of infection ; in others, the specific microbes 

 are wholly responsible for the disease ; and in others, again, 

 the diseased action may be due to the combined action of 

 microbes and their products. 



Some light may be thrown upon the action of these 

 chemical products of microbes by considering the action of 

 similarly constituted bodies. Albuminous substances taken 

 into the system as food are split up by the action of true 

 ferments or enzymes, such as pepsin and trypsin, into simpler 

 substances, amongst which albumoses and peptones are the 

 most important. These bodies in the ordinary process of 

 digestion pass through the liver and help to nourish the system, 

 but if separated before they enter the liver, and injected into 

 the blood directly, they act as violent poisons. Their 

 poisonous action is destroyed by boiling. 



Products of pathogenic microbes have been regarded by 

 chemists as albumoses, their action being destroyed by boihng. 

 Houx and Yersin obtained a " soluble poison " from a cultiva- 

 tion of the bacillus of diphtheria, and found by inoculation 

 that it produced all the symptoms of this disease. 



These products derived from the decomposition of albuminous 

 substances by the agency of microbes partake of the nature 



