THE RELATIONS OF MICRO-ORGANISMS TO DISEASE. 165 



The phenomena of septic intoxication may be induced by the prod- 

 ucts of bacteria] growth outside of the body when these in considerable 

 quantity are in any way taken into it. This is true not only of poisons 

 elaborated outside the body by pathogenic bacteria, but also of many 

 forms of bacteria usually harmless. Thus are caused many forms of 

 food poisoning which simulate but are not actually infectious diseases, 

 because there is no development within the body of the disease-inciting 

 germs. 



Similar local and general effects may be induced in the body by other 

 poisons than those of bacterial origin. Ricin and abrin, for example, 

 well-known vegetable poisons, and the venom of scorpions and of certain 

 snakes are closely similar in their action to the toxins which the bacteria 

 form either within or without the body. 



It should be remembered in this connection that effects closely resem- 

 bling those due to bacterial or allied poison may be induced by toxic 

 agents developed within the body as a result of defective elimination or 

 faulty cell metabolism auto-intoxication (see p. 358). 



Thus the deleterious effects of pathogenic bacteria upon the body are 

 but in small measure simply mechanical. Local necrosis l and inflam- 

 mation, albuminous degeneration of cells, leucocytosis and other altera- 

 tions of the blood, fever, structural lesions and functional disturbances 

 in the nervous system, irregularities in the circulatory and respiratory 

 mechanisms, etc., may follow the distribution in the body of bacterial 

 toxins. 



Proofs of the Infective Nature of Bacteria Found in the 



Body. 



It will be seen, from what has now been said of the bacteria, that in 

 different parts of the system in health, and in a large number of abnor- 

 mal conditions, various forms of bacteria occur ; but it is quite evident 

 that the significance which we must - attach to their mere presence varies 

 greatly. In a large number of cases, especially when on parts exposed 

 to the air or in the gastro- intestinal canal, they are evidently of no more 

 importance than so much inorganic dust. When, however, special forms 

 of bacteria are uniformly present in connection with well-defined dis- 

 eases, or in their lesions, and especially if these largely preponderate, 

 the conjecture is certainly justified that the micro-organisms may have 

 something to do with their incitement. Yet in all such cases we have to 

 consider the possibility that it is the abnormal state of the body or the 

 character of a lesion, brought about perhaps in other ways, which affords 

 conditions suitable for the growth of this form of bacteria, and that these 

 may consequently be present in considerable numbers, while in the ab- 

 sence of such conditions they would be unable to develop. Even the 

 constant occurrence in the body, in certain diseases, of bacteria which 

 evidently produce well-marked local effects, either inflammatory or de- 



1 Sec Flej:ner, "The Pathology of Toxalbuiniu Intoxication," Johns Hopkins Hos- 

 pital Reports, vol. vi., p. 259, 1897. 



