602 PATHOGENIC MICROORGANISMS 



made soon after this by Lassar. 1 Soon after the experiments of Metch- 

 nikoff and Roux, successful inoculations upon lower monkeys (maca- 

 cus) were carried out by Nicolle. 2 Since that time, it has been found 

 by various observers that almost all species of monkeys are susceptible. 

 Simple subcutaneous injection is not sufficient to produce a lesion. 

 The technique which has given the most satisfactory results consists 

 in the cutaneous implantation of small quantities of syphilitic tissue 

 obtained by excision or curetting of primary and secondary lesions. A 

 small pocket is made under the mucous membrane of the genitals or of 

 the eyebrows and the tissue placed in this under aseptic precautions. 

 The inoculation may be made directly from the human being, but can 

 also be successfully carried out from monkey to monkey for many 

 generations. Attempts at transmission from tertiary lesions have so far 

 been unsuccessful. The spirochaetes can be demonstrated both in the 

 primary lesions of the inoculated animal and in the secondarily enlarged 

 glands. The successful inoculation of rabbits with syphilis has been 

 recently performed by Bertarelli. 3 He obtained ulcerative lesions by 

 inoculation upon the cornea and into the anterior chamber of the eye 

 and was able to prove the syphilitic nature of these lesions by finding 

 the spirochsete within the tissue. In these animals, as well as in the 

 lower monkeys, the disease usually remains localized. 



In 1907, Parodi showed that syphilitic lesions could be produced by 

 direct inoculation into the testicles of rabbits. This method of inocula- 

 tion has been subsequently studied by many investigators, especially 

 by Uhlenhuth and Mulzer. 4 It is the easiest method of obtaining 

 spirochaete in any quantity from lesions in man. The spirochaete-con- 

 taining lesions may be either excised or scraped as conditions permit 

 and rubbed up in a mortar with sterile sand, in a few centimeters of 

 sterile human ascitic fluid. This emulsion is then injected directly 

 into the substance of rabbit testicles. A swelling supervenes which 

 is often noticeable after two weeks, and is usually at its height in 5 to 

 7 weeks. At this time the testicle is much larger than normal, some- 

 times evenly swollen and sometimes nodular, and of a firm elastic con- 

 sistency. When taken out at castration it oozes a sticky fluid, both 

 from testicle and tunica, which is rich in actively motile spirochaetes. 

 By continuous transinoculation from one rabbit to another such a strain 

 can be indefinitely carried along. It can be inoculated from rabbits 



1 Lassar, Berl. klin. Woch., xl, 1903. 2 Nicolle, Ann. de 1'inst. Pasteur, 1903. 



' Bertarelli, Cent, f . Bakt., xli, 1906. 



4 Uhlenhuth und Midzer, Arb. a. d. k. Geslmdh'tsamt-, xxxiii, 1909. 



