DETAILS OF METHOD OF OBTAINING THE OPSONIC INDEX 63 



a vaccine or bacterine when injected into a person or animal suffering 

 from the particular chronic infection and having a low opsonic index, 

 will, during the first twenty-four hours, generally lower the index a 

 little more. This is called the negative phase. After the first twenty- 

 four hours, however, the index will rise from day to day, until after 

 the sixth day it is generally considerably above the normal opsonic 

 index. This is called the positive phase. Then the index begins to 

 drop again. If, now, on the sixth or seventh day, another vaccine 

 injection is given, the index instead of going below normal will rise 

 again considerably above normal. It has been found that, very fre- 

 quently, simultaneously with the rise of the opsonic index the general 

 condition of the sick person or animal improves and complete recovery 

 may take place. This vaccine, or, as it is also called, bacterine treat- 

 ment, under guidance of the opsonic index, which has to be ascertained 

 from day to day, is an exceedingly laborious, time-consuming, and 

 delicate task, but it has been tried in man in thousands of cases. It 

 has been found to bring favorable results in chronic local infections 

 of the tubercle bacillus, the staphylococcus, streptococcus, pneumo- 

 coccus, gonococcus, colon bacillus, etc. 



The treatment is not applicable in acute violent infections and 

 in very advanced generalized conditions, as in chronic tuberculosis, 

 acute septicemia, pyemia, pneumonia, etc. 



Details of Method of Obtaining the Opsonic Index. The details 

 of the pro^dure to obtain the opsonic index and to prepare the 

 bacterine or vaccine in the case of a horse suffering from a local chronic 

 staphylococcus infection are as follows: Ascertain by microscopic 

 examination and cultures that the Staphylococcus pyogenes aureus 

 (the common pus-producing staphylococcus) is the cause of the 

 chronic suppuration. The steps now necessary to obtain the opsonic 

 index of the horse's blood (for the Staphylococcus pyogenes aureus) 

 are as follows: 



1. Prepare a culture of the infecting microbes, and grow in the 

 incubator for eighteen to twenty-four hours. Shake well if in bouillon, 

 or if on agar make a suspension in salt solution, then heat in a water 

 bath for one-half hour at 55 C. Shake well again, centrifuge, and 

 pipette off some of the supernatant uniformly cloudy fluid which is 

 a homogeneous emulsion of the Staphylococcus pyogenes aureus. 



2. Get some blood from a healthy horse, allow it to fall into a 

 centrifuge tube containing a 1.5 per cent, solution of citrate of sodium. 

 This fluid will prevent coagulation. Mix well by shaking. Wash as 

 described before in physiologic salt solution; finally, centrifuge well 

 once more. Three layers are formed: the lowest layer of red blood 

 corpuscles, a clear upper fluid layer, and between them a thin grayish 

 red film. The latter contains the white corpuscles. Pipette off the 

 clear fluid. Now, pipette off the leukocytes. They will be mixed 

 with some red corpuscles, but this is of no significance. 



