MECHANICAL ACTION OF BACTERIA 131 



selves. It is extremely doubtful if ptomains are produced in important 

 quantities by pathogenic bacteria infecting living tissues. 



MECHANICAL ACTION OF BACTERIA 



In former years the theory as to the influence of mechanical blocking 

 of vessels with masses of bacteria was regarded with much favor in the 

 etiology of certain infections, particularly anthrax. At the present 

 time this factor has not the same importance, for while it is true that 

 bacterial emboli may occasion harm by blocking important vessels, 

 further researches have shown that it is doubtful if any pathogenic 

 microorganisms are totally devoid of toxic action, and that their toxins 

 are largely responsible for the tissue changes and symptoms of infections. 



It can readily be understood that emboli of microorganisms may 

 produce metastatic lesions; thus when staphylococci are injected into 

 the ear vein of a rabbit they produce abscesses in the kidney and heart, 

 and masses of bacteria from an ulcerative endocarditis, when carried to 

 different portions of the body, will cause abscess formation; but the 

 question in hand, however, deals with the effects of mechanical blocking 

 itself. 



Investigations with anthrax bacilli have shown that they are re- 

 markably free from soluble toxins and endotoxins, although the local 

 lesion develops so rapidly and becomes so quickly necrotic as to suggest 

 very strongly the action of some local toxic substance. Cases of human 

 anthrax seldom prove fatal if the lesion is removed and the blood-stream 

 remains free from the bacilli. Vaughan has shown that anthrax protein 

 possesses toxic qualities, and since the majority of fatal cases of anthrax 

 show enormous numbers of bacilli in the blood-stream and internal 

 organs, it may be that this bacteremia produces an accumulation of 

 toxins which is greatly augmented when the body-cells of the host have 

 produced an antiferment that splits up the protein of the bacilli, the 

 combined toxic substances being responsible for the severe symptoms 

 and death. 



With protozoan disease, the possibility of serious symptoms follow- 

 ing blocking of vessels is far greater, and, indeed, the cerebral symp- 

 toms of malignant malaria and sleeping sickness may be due in part 

 to the blocking of small, but physiologically important, vessels with 

 masses of plasmodia and Trypanosoma gambiensi, together with the ab- 

 sorption of toxic agents and the products of disintegration. Thus Bass, 

 who has successfully cultivated the malarial plasmodium outside of the 



