DIAGNOSIS OF AFRICAN TICK FEVER. 



239 



The following precipitin reactions were performed with the sera of 

 the above animals : 



Conditions ul' reaction. 



Phis serum of- 



Rat 1 (immune to African S) 



Rat 2 (immune to African S) 



Rat 1 (immune to African S) 



Rat 2 (immune to African S) 



Mice 8 to 10 (immune to American &')_._ 

 Mice 11 and 12 (immune to American ,S) 



Mice 8 to 10 (immune to American ,S') 



Mice 11 and 12 (immune to American S) 



Rat 4 (infected with African S) 



Rat 6 (infected with African S) 



Rat 15 (infected with American S)_ 



Rat 4 (infected with African S) - 

 Rat 6 (infected with African S)- 



Do. 



Do. 



Remarks. — There was no trace of a reaction in any of the tubes after 

 two hours, after eighteen hours, or even after forty-eight hours. 



November 13 another of the rats, number 17, infected with American spiro- 

 (jhaeta on November 8, -shows numerous spirochaetse in the circulating blood. 

 The animal was bled to death. Some drops of the fresh blood were mixed with 

 citrate solution; after fifteen minutes the parasites had disappeared and could 

 no longer be found on microscopic examination. It seems probable that the 

 blood was collected just before the crisis, that the parasites were about to undergo 

 bacteriolysis, and that the withdrawal of the blood hastened this reaction. The 

 remainder of the blood collected was centrifugated and the serum separated. 



The following precipitin reactions were performed, the serum of rat 

 number 17 being used for the precipitinogen. 



Conditions 01 traction. 



Serum of— 



Plus serum of— 



Rat 1 (immune to African >S') 



Rat 2 (immune to African £') 



Mice 8 to 10 (immune to American S) 



Mice 11 and 12 (immune to American S)j do 



Rat 17 (infected with American 5)_ 



Remark. — No trace of a reaction occurred in any of the tubes after two 

 and after twenty-four hours. 



In order to be sure that antibodies were already present in the sera 

 of animals numbered 1 and 2 and 8 to 12, attempts were made to test 

 the agglutinative value of the sera with the blood of mice numbered 19 

 and 20, which had been .infected two days previously with African 

 spirochaBtse and with the blood of rat number 17, the blood of which 

 showed a- rich infection with American spirochaetas. However, although 

 the reactions were performed with the blood of mice numbered 19 and 

 20, there were too few parasites present to allow me to arrive at any 



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