PIROPLASMA BIGEMINUM AND ANAPLASMA CENTRALE. 353 



The reactions in Experiment 7, judged by the control bulls 

 4456, 4425, 4421, 4460, and 4463, are much more regular than in 

 the previous experiments. In no case did the Piroplasma bigem- 

 inum survive even 48 hours in citrated blood, or even in 

 defibrinated blood. Anaplasma centralc in practically all cases 

 survived the periods of keeping, though considerable lessening 

 in its virulence undoubtedly occurred. Solutions of citrate in the 

 proportion of 50 to 50 of blood and 30 to 70 of blood appear to 

 be more harmful to the Anaplasma centralc than a 10 to 90 

 proportion. An isotonic solution of sodium citrate did not 

 appear to have any superiority over a 10 per cent, solution. It 

 will be seen from the table that in a few cases the blood of the 

 heifer 4390 containing a strain of Anaplasma marginale, in 

 addition to the redwater strain, in a few cases broke down the 

 ])revious immunuity to Anaplasma coitrale in the bulls. 



Conclusion. 



Judging from the experiments recorded in this paper, 

 Piroplasma higeminum in blood drawn from an immune animal 

 will not survive in citrated blood for periods longer tliaii 24 

 hours, but may survive for that length of time. AnaplasmM 

 centralc will practically always survive for at least 144 hours in 

 citrated blood, if the proportion is not more than 10 of citrate 

 solution to 90 of blood. 



