EXPERIMENTAL INOCULATION 723 



spleen may contain the virus and inoculation of either of these tissues into monkeys 

 may result in infection. 



IV. The lower monkeys. The lower catarrhine monkeys may be infected 

 with syphilis but the proportion of successful inoculations is very variable. 

 Roux and Metchnikoff taking the results of their inoculations of macacus and 

 cynocephalus monkeys together (M. rhesus, M. cynomolgus, M. sinicus, 

 C. hamadryas) succeeded in infecting 50-60 per cent. They affirm that the 

 only chance of success lies in inoculating the material on the orbital arches or 

 genital mucous membrane. In experiments on the same species of monkeys, 

 Finger and Landsteiner infected 87 per cent, by making deep scarifica- 

 tions and inoculating a large amount of the virus. Thibierge and Ravaut 

 say that macacus monkeys can always be infected if inoculated on the free 

 margin of the eyelids. The incubation period is shorter than in the anthropoid 

 apes and averages 23 days. The primary sore takes the form of an ulcer 

 and the subjacent tissue is infiltrated but not characteristically indurated. 

 In M . rhesus the chancre, as a rule, has the appearance of a papule. There 

 is no enlargement of the glands. Secondary lesions have not been ob- 

 served. 



As a result of their experimental inoculations, Roux and Metchnikoff lay 

 down the following law : the shorter the incubation period, the less severe the 

 syphilitic infection. 



V. Rabbits. The rabbit can be infected by inoculating the virus into the 

 eye. Thus, material from hard chancres or secondary papules when inoculated 

 into the anterior chamber of the eye of a rabbit leads to the development of 

 a small swelling of the cornea in 50 per cent, of cases about 10 days after 

 inoculation ; this swelling is subsequently accompanied by a parenchymatous 

 keratitis with a very marked lymphocytosis (Bertarelli). Microscopical 

 examination shows the presence of treponemata in very large numbers in 

 the anterior part of the infected cornea but they are never found in the 

 epithelial layer. If a small portion of the infected cornea be transferred to 

 the anterior chamber of the eye of a normal rabbit a similar lesion containing 

 actively multiplying spirochsetes develops. 



The rabbit virus is capable of infecting monkeys. Bertarelli produced 

 very distinct chancres and syphilitic keratitis in Macacus cynomolgus by 

 inoculating the monkeys either on the cornea or by scarifying the skin with 

 material from the cornea of the fifth passage rabbit. 



Bertarelli's results have been confirmed by Sherber, Greef and Clausen 

 and others. 



To ensure a successful result Bartarelli recommends inoculating the infected tissue, 

 or scraping into the anterior chamber of the eye. Alternatively, the margin of the 

 cornea may be scarified and rubbed with the virus ; it is important that the eyelids 

 be held open for a little while after the operation. The material should previously 

 to inoculation be well washed in sterile water to remove any contamination that 

 may be present on the surface. 



VI. Some of the other lower animals appear to be susceptible to an experi- 

 mental infection with syphilis. 



The rabbit virus on inoculation into guinea-pigs produces keratitis with 

 multiplication of the treponemata (Bertarelli). 



Dogs (Hoffmann and Bruning), sheep (Bertarelli) and cats (Levaditi and 

 Yamanouchi) can all be infected by scarifying the cornea. 



Siegel produced indurated nodules at the site of inoculation in mice 2 days 

 old by inoculating them with the virus of syphilis. The spleen of one of 

 these when inoculated into a monkey produced a very distinct syphilitic 

 lesion. 



