THERAPEUTIC IMMUNIZATION IN MAN 505 



succeeded in transmitting the disease to a chimpanzee, and in March, 

 1905, Schaudinn 135 discovered the treponema pallidum. 



As a matter of fact, probable transmission of syphilis to lower 

 monkeys had been accomplished as early as 1879 by Klebs 136 and 

 subsequently by Neumann, 137 Martineau, 138 and Charles Nicolle, 139 

 but in none of these experiments had it been possible to prove beyond 

 question the syphilitic nature of the inoculation-products. In the 

 chimpanzees inoculated by Metchnikoff and Roux, the animals de- 

 veloped not only primary sores but also secondary eruptions, poly- 

 adenitis, and enlarged spleens in such characteristic manner that the 

 identity of the inoculation disease with human syphilis could no 

 longer be doubted. 



Successful transmission to other anthropoids and to lower mon- 

 keys were then announced, in rapid succession, by Metchnikoff and 

 Roux, Ch. Nicolle, Neisser, Baermann and Halberstaedter, Einger 

 and Landsteiner, jloffman, and others. The susceptibility of mon- 

 keys was tabulated by Neisser in the following series : Chimpanzee, 

 Gibbon, Orang-Outang, Cynocephalus babuin, Cynocephalus sphinx, 

 Cynocephalus hamadryas, Cercopithecus fulginosus, Macacus niger, 

 M. nemestrinus, M. cynomolgus, M. sinicus, M. speciosus, M. rhesus. 

 In 1906 Bertarelli 14 produced syphilitic keratitis in rabbits, dem- 

 onstrating the treponema pallidum in sections of the cornea and in 

 1907 Parodi 141 first produced syphilitic orchitis in the same animals. 



Apart from monkeys and rabbits, no animal species have so far 

 been shown sufficiently susceptible to be available for systematic 

 study. It is true that the production of keratitis is claimed in dogs 

 and sheep (Bertarelli, Hoffman and Briinig), in guinea pigs (Ber- 

 tarelli), in cats (Levaditi and Yamanouchi), and in goats (Ber- 

 tarelli). However, these experiments have been isolated and too 

 uncertain with present methods to offer material for experimentation. 

 Our own attempts on cats, pigs, guinea pigs,- rats, mice, and a few 

 birds, have yielded negative results only. There are many observa- 

 tions of great scientific interest which might be discussed in con- 

 nection with the problem of susceptibility of various animal species, 

 however, we will confine ourselves at present to those phases of the 

 work only which have bearing on the questions of immunity. 



In the fundamental premises, the work on monkeys has pretty 

 accurately confirmed the observations concerning reinoculation and 

 superinfection previously made on human beings. 



135 Schaudinn. Deutsch. med. Wchnschr., 1905, No. 42; Arb. a. d. k. 

 Gsndhtsamte., 1907, xxvi. 



136 Klebs. Arch. f. exper. Path. u. Pharmakol., 1879. 



137 Neumann. Cited from Miihlens, loc. cit. 



138 Martineau. Arch. f. Dermat. u. Syph., 1884, No. 16. 



139 Nicolle, Ch. Cited from Miihlens, loc. cit. 



140 Bertarelli. Centralbl. f. Bakteriol, Orig. xli, 1906, and xliii, 1907. 



141 Parodi. Centralbl. f. Bakteriol., Orig. xliv, 1907. 



