ENDOCARDITIS 



189 



have been found in a few cases of acute tuberculosis, though no 

 vegetative or ulcerative condition is produced. 



In some cases, though we believe not often, the organisms 

 may attack healthy valves, producing a primary ulcerative endo- 

 carditis, but more frequently the valves have been the seat of 

 previous endocarditis, secondary ulcerative endocarditis being 



FIG. 61. Section of a vegetation jn 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. 



thus produced. 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 vegetations are composed for 

 the most part of unorganised material, they do not offer the 

 same resistance to the growth of bacteria, when a few reach them, 

 as a healthy cellular tissue does. On microscopic examination 

 of the diseased valves the organisms are usually to be found in 

 enormous numbers, sometimes forming an almost continuous layer 

 on the surface, or occurring in large masses or clusters in spaces 

 in the vegetation (Fig. 61). By their action a certain amount 



