THERAPEUTIC IMMUNIZATION IN MAN 507 



virulent treponemata. In seven animals only did the inoculations 

 with organ-substance fail to produce lesions, but of these all but one 

 died before the 30th day after inoculation. 



In contrast to these results Neisser found that animals which had 

 been "cured" by various treponemacidal agents such as atoxyl, 

 arsacetin, etc., were almost regularly reinoculable. In fact, these 

 experiments were so uniform that Neisser later utilized the reinocu- 

 lation method as an index of cure or persistence of the disease. 



The results obtained in monkeys, therefore, are very similar to 

 those determined by clinical observations in man, and the following 

 statements may be taken as summarizing the conditions revealed by 

 monkey experiment. 



1. That the body develops resistance, progressively increasing 

 as the virus becomes generally distributed. 



2. That the resistance probably reaches its highest development 

 during the early tertiary period. 



3. That complete cure is probably synonymous with gradual 

 return of susceptibility. 



The only other animals on which systematic experimentation has 

 been possible up to the present time have been rabbits. Since 

 Bertarelli's successful production of keratitis and Parodi's inocula- 

 tion of the testes in these animals, they have been studied carefully 

 by a number of workers, chiefly Uhlenhuth and Mulzer, 144 and 

 Noguchi 145 ; and in our own laboratory, with Hopkins and Mc- 

 Burney, the writer has observed rabbit syphilis for a number of 

 years. From a large mass of observations it appears that the condi- 

 tions in rabbits are not identical with those observed in man and 

 monkeys. So far, the testes and the eyes are the only organs in, 

 these animals in which syphilitic lesions can regularly be produced, 

 and although treponema pallidum may apparently be distributed 

 generally to the organs after inoculation, it does not easily arouse 

 pathological reactions except in the organs named, and the lesions 

 produced are not accompanied by a generalized resistance compar- 

 able to that discussed in connection with the higher animals in pre- 

 ceding sections of this paper. 



Bertarelli found that he could reinoculate the cornea in a rabbit 

 that had previously been inoculated with syphilis. Uhlenhuth and 

 Mulzer, and Neisser and Piirckhauer, showed that infections of the 

 eye could be produced while the opposite eye was still syphilitic. 

 Tomazewski found that scrotal infection did not protect against in- 

 fection of the cornea, and vice versa. Furthermore, Uhlenhuth and 

 Mulzer, on the basis of a very thorough study, believe that such rein- 

 fections are neither less extensive nor more rapid in healing than 



144 Uhlenhuth and Mulzer. Arb. a. d. k. Gsndhtsamte., 1913, xliv. 



145 Noguchi, H. Jour. Am. Med. Assn., 1912, Iviii, 1163. 



