198 INFLAMxMATORY AND SUPPURATIVE CONDITIONS. 







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conditions elsewhere, c.o-. in osteomyelitis, in septic inflamma- 

 tions of the urinary passages, in pyaemia and septicasmia, in the 

 course of or following infective fevers, and not very infrequently 

 as a sequel to acute pneumonia. In some cases, especially 

 when the valves have been previously diseased, the source of 

 the infection is quite obscure. It is evident that as the vege- 

 tations are composed for the most part of unorganised mate^ 

 rial, they do not offer the same resistance to the growth of 



bacteria, when 

 ift ^ ,i- .'-.,'■ :■ a few reach 



them, as a 

 healthy cellu- 

 lar tissue does. 

 On micro- 

 scopic exami- 

 nation of the 

 diseased valves 

 the organisms 

 are usually to 

 be found in 

 «- ----^T ».-^»,^Bajp- 'My enormous num- 



times tormmg 

 an almost con- 

 tinuous layer 

 on the surface, 

 or occurring in 

 large masses 

 or clusters in 

 spaces in the 

 vegetation (Fig. 75). By their action a certain amount of 

 softening or breaking down of the vegetations occurs, and the 

 emboli thus produced act as the carriers of infection to other 

 organs, and give rise to secondary suppurations. 





Fig. 75. — Section of a vegetation in ulcerative endocarditis, 

 showing numerous staphylococci lying in the spaces. The lower 

 portion is a fragment in process of separation. 



Stained by Gram's method and Bismarck-brown. X 600. 



Experimental. — Occasionally ulcerative endocarditis is produced by the 

 simple intravenous injection of staphylococci and streptococci into the circula- 

 tion, but this is a very rare occurrence. It often follows, however, when the 

 valves have been previously injured. Orth and Wyssokowitsch at a com- 

 paratively early date produced the condition by damaging the aortic cusps by 

 a glass rod introduced through the carotid, and afterwards injecting staphylo- 



