522 SYPHILIS 



not attenuated in virulence. Uhlenhuth and Mulzer produced 

 generalised syphilitic lesions in young rabbits by intracardiac 

 inoculation with syphilitic material. They have also found 

 that the organism can pass through the placenta of the rabbit 

 and infect the foetus. 



It has long been held that a person suffering from syphilitic 

 disease is not susceptible to a fresh infection, and this has been 

 shown by experimental methods to hold in the artificially pro- 

 duced disease in the ape, the possibility of re-inoculation thus 

 indicating freedom from infection. A considerable number of 

 cases in the human subject have been observed where after 

 treatment with salvarsan a second attack of the disease has been 

 contracted, the inference being that the first attack had been 

 completely cured. In the case of the rabbit, however, it has 

 been found possible to produce a fresh syphilitic lesion when 

 another was still in existence on the cornea. Apparently in this 

 animal the effects of this local lesion do not become general in 

 the same way as in maji. 



The experimental production of the disease has supplied us 

 with some further facts regarding the nature of the virus. It 

 has been shown repeatedly that the passage of fluid contain- 

 ing the virus through a Berkefeld filter deprives it completely 

 of its infectivity ; in other words, it does not belong to the 

 ultra^microscopic group of organisms. The virus is also 

 readily destroyed by heat, a temperature of 51° C. being 

 fatal. With regard to the production of immunity, very little 

 of a satisfactory nature has so far been established. It has been 

 found that the virus from a macaque monkey produces a less 

 severe disease in the chimpanzee than the virus from the human 

 subject, inasmuch as secondary lesions do not follow ; the virus 

 would thus appear to have undergone a certain amount of 

 attenuation in the tissues of that monkey. The presence of the 

 spirochsete does not lead to the formation of anti-substances to 

 any marked extent. There is some evidence that the serum 

 from a patient suffering from the disease when mixed with the 

 virus before inoculation modifies the disease to a certain extent, 

 but further evidence on this point is necessary. 



Luetin. — Koguchi has prepared an extract from pure cultures 

 of the spirochsete pallida, which he calls luetin, and he finds that 

 this gives a characteristic cutaneous reaction in syphilitics. . This 

 reaction is analogous to the tuberculin reaction in tuberculosis, 

 and, like it, appears to depend on a condition of super-sensitive- 

 ness or allergy (p. 595). In a normal individual the intradermic 

 inoculation of luetin produces a local erythema which may 



