BACTERIA IN DISEASE. 1 59 



cinoma, chronic nephritis, arteriosclerosis, and in many other 

 diseases. 



Concerning terminal infections Osier says: "It may seem 

 paradoxical, but there is truth in the statement that persons 

 rarely die of the disease with which they suffer. Secondary infec- 

 tions, or, as we are apt to call them in hospital work, terminal 

 infections, carry off many of the incurable cases in the wards." 



The term secondary infection is also used for the modifi- 

 cation of an infectious process which has been in existence 

 for some time, by infection with a second variety of bacteria. 

 That takes place, for instance, in pulmonary tuberculosis, 

 when the invasion of the already tuberculous lungs by the pyo- 

 genic micrococci assist in the formation of cavities. In this 

 sense it will be seen that the term secondary infection is used 

 as a name for a variety of mixed infection. In the secondary, 

 mixed and terminal infections, the bacteria which enter secon- 

 darily are likely to be of the pus-producing varieties, especially 

 the streptococcus pyogenes. 



As to the mechanism which bacteria make use of in order 

 to produce disease, according to our present knowledge, they 

 work chiefly through the poisonous substances formed by them 

 and deposited in the bodies of the persons suffering from the 

 disease. The theory that bacteria have an important influence 

 through the destruction of substances taken by them from the 

 body of the patient for food is no longer entitled to much weight ; 

 neither are we able in most cases to account for the phenomena 

 of disease by any mechanical action on the part of the bodies 

 of bacteria. That such action does occasionally take place 

 may be seen in experimental anthrax in mice, where the blood- 

 capillaries of the liver and kidneys may be completely plugged 

 with masses of anthrax bacilli. The diseases in which the cir- 

 culating blood is swarming with bacteria are much commoner 

 in the lower animals than in man. 



Toxemia. — By toxemia is meant the absorption of poisonous 



