DIAGNOSIS OF AFRICAN TICK FFVFR. 



237 



The blood serum tested for the precipitin was collected from animals 

 which had received one, two and three separate infections of spirocliEet* 

 respectively, and from which the spirochete had disappeared so far as 

 could be determined by microscopical examination. 



Since it has been observed in the study of the precipitin reaction that 

 the precipitin is sometimes soluble in an excess of precipitable substance, 

 and that there must exist a certain quantitative relationship between the 

 amount of precipitin and precipitable substances for the optimum reac- 

 tion, many of these experiments were also performed in various dilutions 

 of the sera. Finally, these same sera were examined for the presence of 

 agglutinins, and in some instances for bacteriolysins. 



The following series of experiments illustrates the value of the pre- 

 cipitin reaction for diagnostic purposes in this disease. 



EXPERIMENTS. 

 SERIES NO. I. 



Mouse No. 1 inoculated on two different occasions with African Spirochwta 

 recurrent; the last inoculation ten days previously. Microscopic examination 

 shows no spirochete in the circulating blood. 



Mouse No. 2 inoculated on two previous occasions with the American spiro- 

 cheta; the last inoculation twelve days previously. Microscopic examination of 

 blood negative for spirochete. 



Mouse No. 3 inoculated three days previously with the African spirochwta. 

 Microscopic examination shows very few spirochete present in the circulating 

 blood. 



Mouse No. J/ inoculated three days previously with the American spirochete 

 Microscopic examination shows very rich infection with spirochete. 



All four animals were bled to death; the blood placed on ice over night; " r 

 the next morning it was centrifugated, the serum drawn off from the clot and 

 reeentrifugated in each instance. All sera were obtained clear. The following 

 reactions were performed: 



Conditions of reaction. 



Precipitin 

 reaction. i 



Serum of— 



Plus serum of — 



Mouse 1 (immune to African S.). 

 Mouse 1 (immune to African S.)_ 



Mouse 3 (infected with African spirochseta) ___ 

 Mouse 4 (infected with American spirochetal 



do 



Negative. 

 Slight cloud- 

 ing o£ the i 

 mixture of 

 sera. 

 Negative. 

 Do. 

 Do. 

 Do. 



Mouse 2(immune to American S.) 



Mouse 3 (infected with African spirocha;ta)___ 

 do 



Normal mouse - 



Mouse 4 (infected with American spirochetal 



" 7 It was thought advisable to allow the blood containing the spirochete to 

 stand over night in order to aid in the breaking up of the spirochete and thus 

 favor the passing of the soluble albumens into the serum. 



