DISEASES CAUSED BY SPIROCHETES 603 



times evenly swollen and sometimes nodular, and of a firm elastic con- 

 sistency. When taken out at castration it oozes a sticky fluid, both 

 from testicle and the tunica, which is rich in actively motile spirochaetes. 

 By continuous transinoculation from one rabbit to another such a strain 

 can be indefinitely carried along. It can be inoculated from rabbits 

 to monkeys and vice versa. This method as well as Noguchi's cul- 

 tivations have opened a new era of spirochsete investigation. It is 

 stated by some observers that intravenous inoculation of rabbits may 

 be followed by localization in the testis and occasionally gununatous 

 infections in other parts of the body have been induced after such 

 inoculation by Uhlenhuth, Mulzer, and others. 



Immtinization in Syphilis. — It is a well-known fact observed by 

 clinicians that one attack of syphilis usually protects the infected in- 

 dividual at least from the development of another chancrous lesion. 

 That this immunity develops quite rapidly was shown by Metchnikoff 

 and Roux, who found that reinfection of a monkey was possible if 

 attempted within two weeks of the first inoculation, but was unsuccess- 

 ful if delayed beyond this period. 



On the basis of this knowledge as to the actual development of an 

 immunity, Metchnikoff,' Finger and Landsteiner,^ and others have 

 made extensive attempts to devise some method of active immunization. 

 Working along the hne of Pasteur's original attenuation of virus, these 

 observers attempted to attenuate the syphilitic virus by repeated pas- 

 sage through monkeys. These- experiments were entirely without suc- 

 cess, the last-mentioned observers finding absolutely no attenuation 

 after twelve generations of monkey inoculation. 



The study of rabbits has permitted a little more definite formulation 

 of our ideas on syphilis immunization. Bertarelli and others have 

 shown that the production of a syphiUtic lesion on the cornea of 

 one eye does not protect against an inoculation subsequently done 

 on the other eye. Apparently rabbits that have been inoculated 

 with spirochaete material and that have not developed syphilitic 

 disease can be successfully inoculated on subsequent attempts. The 

 offspring of female rabbits with syphilis of the cornea are, according 

 to Muhlens, not immune. 



There is no evidence so far that specific therapy or trea,tment with 

 spirochaete material has had favorable influence upon the disease except 



' Metchnikoff, Arch. g6n. de m6d., 1905. 



' Finger und Landsteiner, Sitzungsber. d. Wien. Akad. d. Wiss., 1905. 



