DISEASES CAUSED BY SPIROCH^ETES 603 



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 gummatous 

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

 oculation by Uhlenhuth, Mulzer, and others. 



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

 clinicians that during active syphilis the patient cannot be superin- 

 fected. That this resistance 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 unsuccessful if delayed beyond this period. 



On the basis of this knowledge, Metchnikoff, 1 Finger and Land- 

 steiner, 2 and others have made attempts to devise some method of im- 

 munization. They attempted to attenuate the syphilitic virus by re- 

 peated passage through monkeys. These experiments were unsuccess- 

 ful, the last-mentioned observers finding absolutely no attenuation 

 after twelve generations of monkey inoculation. 



Bertarelli and others have shown that the production of a syphilitic 

 lesion on the cornea of one eye does not protect against an inoculation 

 done on the other. Rabbits that have been inoculated ^vith spirochsete 

 material and that have not developed syphilitic disease can be success- 

 fully inoculated on subsequent attempts. The offspring of female rab- 

 bits with syphilis of the cornea are, according to Muhlens, not immune. 



There is no evidence so far that specific therapy or treatment with 

 spirochsete material has had favorable influence upon the disease. 

 Chemotherapy has had results analogous to those obtained in- 

 man. 3 



Attempts at passive immunization have been entirely without success. 



Investigations carried on in our own laboratory in the last three 

 years have shown definitely, we think, that immunization of animals 

 with culture pallida produces antibodies, agglutinins, treponemacidal 

 substances, entirely analogous to similar substances produced against 

 bacteria. However, there is a biological change which takes place 

 when treponema pallidum is cultivated. The antibodies produced 

 with the culture pallida have no action whatsoever upon the virulent 



1 Metchnikoff, Arch. ge"n. de me"d., 1905. 



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



* Von Prowazek, "Handbuch der pathogenen Protozoen," i, 1912, Leipzig, Bartsch. 



