512 INFECTION AND RESISTANCE 



generations in lower monkeys. The lesion which developed was very 

 slight, consisting only of a local induration, and no generalized symp- 

 toms developed. A previous attack of syphilis Metchnikoff believes 

 could be reliably excluded in the subject. The experimenters suggest 

 that the passage through lower monkeys may attenuate the virus for 

 man, this leading to relative immunity to subsequent inoculations, 

 and furnish a possible means of protection. Their experiments are 

 too few to permit conclusions as yet, but even should they hold good, 

 the method would seem to imply a considerable degree of risk and 

 our experience with superinfections and reinfections in syphilis does 

 not encourage the hope that a method so drastic would be justified 

 when the benefit to the patient is apt to be of such duration only. 



The history of passive immunization is an extensive one and 

 hardly worth going into with any degree of detail since many times 

 extravagant claims have been made only to be refuted by accurate 

 study. There is a great similarity in respect to this between syphilis 

 studies and those in tuberculosis and cancer. A brief examination of 

 the bibliography in Neisser's book is sufficient to convince one of the 

 many attempts that have been made in this direction and often by 

 methods as ludicrous as the claims of success for which they formed 

 the basis. The most careful and skillful workers have uniformly 

 reported failure. Metchnikoff and Roux treated various monkeys 

 with blood from syphilitic patients and used the serum of these ani- 

 mals for protective experiments. There are a few instances in which 

 mixtures of such serum with syphilitic virus rendered this inactive 

 on inoculation. A powder made of this serum was supposed to have 

 some protective effect when applied to fresh inoculation spots within 

 the first hour after inoculation. However, injection of the serum 

 had no effect whatever. Casagrandi and de Luca using serum of a 

 dog treated with syphilitic virus, obtained entirely negative results, 

 and Finger and Landsteiner 155 report negative results with monkey 

 blood in man. The most extensive experiments were again those 

 carried out by Neisser and his associates. They were done by the 

 treatment of animals with dead and living syphilis virus, organ 

 extracts, with the blood of syphilitic man and monkey, and horses, 

 sheep, and monkeys were used for the production of "immune" 

 serum. In no case was there the slightest protective effect on the 

 part of the serum either in vitro or in vivo, and the results of the 

 experiment were unqualifiedly negative. 



When the method of complement fixation was successfully ap- 

 plied to the diagnosis of syphilis first by Detre, and then by Wasser- 

 mann, Neisser and Bruck, 156 it was generally assumed that this 

 reaction incidentally demonstrated that specific antibodies were 



155 Finger and Landsteiner. Centralbl. /. Bakteriol., Ref. xxxviii, 1906. 



156 Wassermann, A., Neisser, A., and Bruck, C. Deutsch. meet. Wchnschr., 

 1906, xxxii, 755. 



