144 TYPHUS IN GUINEA-PIGS 



wards confirmed by Ricketts and Wilder (1910), Gavifro and 

 Gerard (1910 2 - 3 ), Anderson and Goldberger (1912). Nicolle 

 (1917) showed that typhus could be maintained indefinitely 

 in the guinea-pig by successive passages and that on the whole 

 guinea-pigs were more reliable animals for this purpose than 

 the lower monkeys. 



Examples of the transmission of typhus to guinea-pigs by 

 the injection of louse viscera and by human blood are given 

 in the protocols (p. 53) of the experiments done to ascertain 

 the specificity of Rickettsia prowazeki for typhus infected 

 lice. 



Our experiences in maintaining two strains of the virus for 

 a period of over a year in guinea-pigs are of sufficient value 

 to warrant brief presentation, together with the results of 

 louse and human blood injections. The records of these strains, 

 patient 116 strain started by the injection of blood from a 

 patient, and Louse Box xvm strain, started by the injection 

 of the viscera of louse 224, are shown in Charts 1 and 2. 



1. METHODS OF INOCULATION 



Whole blood drawn from the aseptically exposed heart of 

 a deeply anaesthetized guinea-pig was invariably used in the 

 inoculations from guinea-pig to guinea-pig. The syringe used 

 was rinsed with a thirty per cent sterilized solution of sodium 

 citrate and thoroughly emptied; a method which insures 

 against clotting of the blood during the one or two minutes 

 required for the procedure of drawing the blood and the in- 

 jection of several guinea-pigs. 



The heart of the donor was exposed, after removing the 

 skin over the chest and abdomen, by cutting a window in the 

 chest wall with red hot scissors. 



Intraperitoneal inoculations were employed in the main- 

 tenance of the two strains which have been carried to the 

 present time, one from patient 116 (guinea-pig 5) since May 

 13, 1920, Chart 1, and one from Louse Box xvm (guinea-pig 

 23) since May 15, 1920, Chart 2. 



