480 SPIRILLUM (SPIROCH/ETE) OBERMEIERI. 



the attack of fever. Their numbers vary very greatly. 

 Outside the body, when kept in blood serum or in -?> per 

 cent, salt solution, the spirilla retain their movement 

 for a considerable time; but as yet we have not succeeded 

 in obtaining any decided multiplication in any sort of 

 nutrient substratum, nor can a cultivation be carried on 

 through several generations. 



Inoculation of On the other hand the disease, characterised by its 

 a ^acks of fever and by the appearance of the spirilla, can 

 be inoculated on monkeys, by means of human blood 

 containing spirilla. Koch and Carter were able, in the 

 case of long-tailed macaques, to set up a typical attack 

 of fever by subcutaneous injection of a small quantity of 

 defibrinated blood, containing spirilla, after an incuba- 

 tion period of several days; during the attack of fever 

 the blood showed large numbers of spirilla, while the 

 organisms were never found either before or after the 

 appearance of the fever. Numerous spirilla could also 

 be demonstrated in the organs of the animals killed at 

 the height of the febrile attack. True relapses, such as 

 are characteristic in man, did not occur in monkeys; the 

 most that took place was that, a few days after the crisis, 

 the temperature was again for a short time elevated, but 

 without any appearance of the spirochiete in the blood. 

 The disease can be inoculated from one monkey to 

 another, but only by means of blood containing spirilla. 

 Monkeys are not protected from recurrence by one attack 

 of the disease : Koch and Carter were able to set up the 

 same typical attack of fever when the monkeys which had 

 recovered from the first attack were inoculated again, after 

 some days or weeks, with blood containing the spirilla. 



From the constant and exclusive occurrence of these 

 peculiarly-shaped bacteria in relapsing fever, and from 

 the fact that the disease can only be set up in healthy 

 monkeys by blood which contains these spirilla in the 

 living condition, we may with certainty conclude that the 

 spirilla are the causal agents of this disease, even although 

 we have not as yet succeeded in cultivating the organisms, 

 and in studying their characters more minutely. 



