WRIGHT'S VACCINE TREATMENT. 187 



counts of a series (3 to 4) of normal sera or first equally mix the different 

 sera, and take the phagocytic count of the pool. 



Normal sera should not differ from one another in a tubercular opsonic 

 estimation by more than 10 per cent. 



Wright's Vaccine Treatment. 



As has been said, the principle of Wright's vaccine treatment depends 

 upon the immunization with small doses of dead bacteria, so-called vaccines, 

 whereby the opsonic index of the individual is raised. This is usually 

 associated clinically, with improvement in the patient's condition. 



The effect of the immunization according to Wright depends upon: 



1. Individual reaction of the patient. 



2. Preparation of the vaccine. 



3. Dosage and form of application. 



The individual reaction of the patient can be measured by the opsonic 

 index. 



As for the preparation of the vaccine, Pasteur's contention that a vaccine 

 must necessarily be made up of living cultures has not proved itself correct. 

 Carefully killed cultures suffice in almost all cases. An example of the 

 preparation of Wright's vaccine is here given. 



The Preparation of a Staphylococcus Vaccine. 



Agar cultures are grown for twenty-four hours, and about 3 c.c. of sterile 

 normal saline solution is added to each culture. The growth is washed off 

 into the saline solution by means of a platinum needle or freshly prepared 

 capillary pipette. The suspension of bacteria is placed into a sterile tube, 

 the end of this tube drawn out in the blow-pipe flame and sealed. The 

 drawn out portion should be about 2 inches in length and as strong as 

 possible. The emulsion is now vigorously shaken for fifteen minutes. The 

 extremity of the drawn-out tube is then cut and a few drops of the emulsion 

 expelled into a clean watch glass, or a small part of the drawn-off end is cut 

 off so that a portion of the emulsion is still contained within it. The tube is 

 resealed, and then submerged in water and kept at 60 for one hour. This 

 usually suffices to kill the bacteria. 



The small amount placed into the watch glass or in the capillary test- 

 tube serves for the standardization, which is carried out as follows: A 

 pipette and rubber bulb as prepared for the opsonic-index test, is also used 

 here. A volume of freshly drawn blood of known corpuscular content, best 

 taken from the worker's own finger, and an equal unit volume of bacterial 

 emulsion is mixed thoroughly with six or seven volumes of i 1/2 per cent, of 

 citrate solution; several even films which may be fairly thick, are then 



