188 INFLAMMATION AND SUPPUBATION 



point of infection cannot be found, but its use is scarcely 

 necessary. 



The paths of secondary infection may be conveniently sum- 

 marised thus : First, by lymphatics. In this way the lymphatic 

 glands may be infected, and also serous sacs in relation to the 

 organs where the primary lesion exists. Second, by natural 

 channels, such as the ureters and the bile-ducts, the spread 

 being generally associated with an inflammatory condition of the 

 lining epithelium. In this way the kidneys and liver respectively 

 may be infected. Third, by the blood vessels : (a) by a few 

 organisms gaining entrance to the blood from a local lesion, and 

 settling in a favourable nidus or a damaged tissue, the original 

 path of infection often being obscure ; (b) by a septic phlebitis 

 with suppurative softening of the thrombus and resulting em- 

 bolism ; and we may add (c) by a direct extension along a vein, 

 producing a spreading thrombosis and suppuration within the 

 vein. In this way suppuration may spread along the portal vein 

 to the liver from a lesion in the alimentary canal, the condition 

 being known as pylephlebitis suppurativa. 



Although many of the lesions produced by the bacteria 

 under consideration have already been mentioned, certain con- 

 ditions may be selected for further consideration on account of 

 their clinical importance or bacteriological interest. 



Endocarditis. There is now strong presumptive evidence 

 that all cases of endocarditis are due to bacterial infection. In 

 the simple or vegetative form, so often the result of acute 

 rheumatism, the micrococcus rheumaticus (p. 193) has been 

 cultivated from the valves in a certain number of cases, and is 

 probably the causal agent in most instances. 



Endocarditis of the ulcerative type may be produced by 

 various organisms, chiefly pyogenic. Of these the staphylococci 

 and streptococci are most frequently found. In some cases of 

 ulcerative endocarditis following pneumonia, the pneumococcus 

 (Fraenkel's) is present ; in others pyogenic cocci, especially 

 streptococci. Other organisms have been cultivated from 

 different cases of the disease, and some of these have received 

 special names ; for example, the diplococcus endocarditis encap- 

 sulatus, bacillus endocarditidis griseus (Weichselbaum), and 

 others. In some cases the bacillus coli communis has been found, 

 and occasionally in endocarditis following typhoid the typhoid 

 bacillus has been described as the organism present, but further 

 observations on this point are desirable. The gonococcus also 

 has been shown to affect the heart valves (p. 225), though this is 

 a very rare occurrence. Tubercle nodules on the heart valves 



