516 SYPHILIS 



along the main caravan routes 11 per cent, contained spirilla, 

 and in some localities almost half of the ticks were infected. 

 In places removed from the main lines of commerce he still 

 found them, though in smaller number. It has also been 

 demonstrated that in some places the ticks are found to be 

 infected with the spirochsetes although the inhabitants do not 

 suffer from tick fever, a circumstance which is probably due to 

 their having acquired immunity against the disease. 



It is now generally believed that the sp. Duttoni is a species 

 distinct from, though closely allied to, the organisms of the 

 relapsing fevers described above. We have mentioned some 

 differences in the clinical characters of the diseases, and there 

 are also differences in the pathogenic effects of the organisms on 

 inoculation. The sp. Duttoni, for example, produces a much 

 more severe disease in monkeys, and is pathogenic to more 

 species of the laboratory animals than the sp. Obermeieri. The 

 most important differences are, however, brought out by immunity 

 reactions. It was shown by Breinl that the immunity produced 

 by the sp. Obermeieri did not protect against the sp. Duttoni, 

 and that the converse also held good ; and it has since been 

 established that a similar difference obtains between the sp. 

 Duttoni and the organisms of the Asiatic and American varieties 

 of relapsing fever. Corresponding results are obtained on 

 testing the various serum reactions in vitro. 



Levaditi succeeded in obtaining cultures of the spirochaete 

 of tick fever by inoculating sacs filled with monkey's serum, 

 heated at 70 C., and placing the sacs in the peritoneal cavity of 

 a rat or rabbit ; when opened at the end of five to seven days, 

 the sacs were found to contain an abundant growth of spiro- 

 chsetes, some of which were of unusually great length. Growth 

 was maintained in similar sub-cultures, and the virulence was 

 well preserved. 



SYPHILIS. 



Up till quite recent times practically nothing of a definite 

 nature was known regarding the etiology of syphilis. Most 

 interest for a long time centred around the observations of 

 Lustgarten, who in 1884 described a characteristic bacillus, 

 both in the primary sore and in the lesions in internal organs. 

 This organism occurred in the form of slender rods, straight, or 

 slightly bent, 3 to 4 /A in length, often forming little clusters 

 either within cells or lying free in the lymphatic spaces ; it took 

 up basic aniline dyes with some difficulty, but was much more 



