LOCAL LESIONS. 149 



On the other hand, the nodules in disseminated tubercle 

 or glanders are much more numerous in the spleen than in 

 the kidneys, which in the latter disease are usually free 

 from them. The important point is that the position 

 of the disseminated lesions is not to be explained by 

 a mechanical process, such as embolism, but depends 

 upon a special relation between the organisms and the 

 tissues, which may be spoken of either as a selective 

 power on the part of the organisms or a special suscepti- 

 bility of tissues, possibly in part due to their affording to 

 the organisms more suitable conditions of nutriment. 

 Even in the case of the lesions produced by dead tubercle 

 bacilli, a certain selective action is found. 



Acute Local Lesions. The local inflammatory reaction 

 presents different characters in different conditions. It 

 may be accompanied by abundant fibrinous exudation, or 

 by great catarrh (in the case of an epithelial surface), or 

 by haemorrhage, or by oedema ; it may be localised or 

 spreading in character ; it may be followed by suppuration, 

 or may lead to necrosis. A few examples may be given. 

 A great many different organisms cause an abundant 

 fibrinous exudation. This, along with necrosis of epi- 

 thelium, is the action of the diphtheria bacillus on a mucous 

 membrane, and also of streptococci in certain conditions ; 

 it is produced in the alveoli of the lung in croupous 

 pneumonia by the pneumococcus and probably by other 

 organisms, whilst fibrinous inflammation in serous cavities 

 is produced by a great many different bacteria. The last 

 statement also applies to numerous suppurative and catar- 

 rhal conditions. The inflammatory change in a Peyer's 

 patch in typhoid fever, though fibrinous exudation is less 

 marked, is followed by necrosis, while in the malignant 

 pustule of man, necrotic change attended by considerable 

 haemorrhage is one of the chief features. The great variety 

 in local reaction is well illustrated in the case of skin lesions 

 produced by bacteria. The necrotic or degenerative changes 

 affecting especially the more highly developed elements are 

 chiefly produced by the direct action of the bacterial 



