PATHOGENIC SPECIES 41 



have been thought by some workers to be different stages in the 

 life history of a single organism. 



Spirochaetes living in animal bodies have a strong tendency to 

 localize in definite parts of the body or in special tissues. The 

 spirochsetes which choose the mouth, the teeth or the digestive 

 tract as a habitat have already been mentioned. Spirochceta 

 bronchialis confines itself to the respiratory tract, causing a cer- 

 tain type of bronchitis. Sp. schaudinni localizes in skin tissue, 

 causing ulcers, in certain tropical countries; Sp. icterohemorrhagice, 

 although probably invading many parts of the body, especially 

 affects the liver and kidneys; the spirochsetes of the various types 

 of relapsing fever confine themselves to the blood; Sp. pertenuis, 

 the cause of yaws, produces a local sore followed by a general in- 

 vasion of the body, but it returns to the skin tissues and settles 

 there; Sp. pallida, of syphilis, is able to produce lesions almost 

 anywhere in the body, but in any given case usually attacks 

 some special organ or tissue, such as the central nervous system, 

 skin, bones, reproductive system, arteries, etc. Other spiro- 

 chsetes have been found in connection with many different 

 maladies, for instance, Sp. orientalis in " ulcerating granuloma 

 of the pudenda," an ulceration which spreads over the skin 

 and mucous membranes of the external genital organs; Sp. 

 vincenti in Vincent's angina, a diphtheria-like affection of the 

 tonsils and throat; Sp. bronchialis in certain types of bron- 

 chitis; and Sp. balanitidis in balanitis, an erosion or ulceration 

 of the glans of the penis. There seems to be more or less 

 evidence that the spirochsetes found in connection with these 

 diseases, often associated with bacteria of various kinds, may 

 be at least partially responsible for them, but to prove this is a 

 very difficult matter. 



In general the diseases caused by spirochsetes may be divided 

 into three groups. The first of these is the type in which the 

 organisms live in the blood and cause general symptoms, such as 

 fever, spleen enlargement, and anemia, and have a tendency to 

 cause relapses. Of such a nature is rat-bite fever and the vari- 

 ous forms of relapsing fever. Second, there is the type in which 

 there are general constitutional symptoms often preceded by a 

 local lesion of some kind, followed later by a localization of the 

 organisms in special organs or tissues. This type, characterized 

 by continued or remittent attacks rather than by short relapses, 



