PROPHYLACTIC VACCINATION 277 



Gates recently standardized his bacterial suspension by measuring the opacity 

 of the suspension by the length of the column of the suspension required to cause 

 the disappearance of a wire loop. By a simple formula the measured opacity is 

 translated into terms of the concentration of bacteria per cubic centimeter and so 

 made comparable with that of other suspensions of the same organism. 



The stock suspension after estimation of the number of organisms contained 

 is ready for dilution. Shera employs the following method for dilution. Suppose 

 the suspension is found to contain 6400 million organisms per cubic centimeter, 

 and that a vaccine of 1000 millions per cubic centimeters is required. Five cubic 

 centimeters are measured out accurately after shaking well, and they are made 

 up to 6400/1000 parts, i.e., 6.4 parts. Multiply 6.4 x 5 and the result 32 equals the 

 volume in cubic centimeters to which the 5 c.c. should be made up. The suspension 

 is sterilized by means of heat. For staphylococci and streptococci 59 to 60 C. 

 for half an hour is sufficient ; for typhoid bacilli 50 to 56 C. for an hour is 

 usually employed. It is best to add some preservative as phenol or tricresol (0.3 

 to 0.5 per cent.) to the suspension and to have the suspension in sealed ampoules 

 preferably of brown glass before immersing in the water bath. Connor success- 

 fully sterilized his staphylococcic vaccines by means of fluorides. After steriliza- 

 tion an ampoule should be opened so that a culture may be made. No vaccine 

 should be used until a culture is found to show no growth. If ampoules are not 

 at hand they may be made from test tubes or the vaccine may be kept in sterile 

 bottles with rubber stoppers or caps. 



Dosage of Organisms. For gonococci, bacillus coli, streptococci 

 and pneumococci 5,000,000 to 50,000,000 are usually employed, while for 

 staphylococci 200,000,000 to 1,000,000,000. Wilson gives the following 

 minimum and maximum doses : Streptococcus, 6 and 68 millions ; 

 staphylococcus, 150 and 900 millions; gonococcus, 45 and 900 millions; 

 meningococcus, 300 and 900 millions; micrococcus melitensis, 700 and 

 1400 millions; bacillus coli, 16 and 240 millions; bacillus typhosus for 

 treatment, 100 and 250 millions; bacillus typhosus for prophylaxis, 500 

 and 1000 millions; bacillus pyocyaneus, 34 and 1000 millions; bacillus 

 pneumonia, 44 millions; bacillus tuberculosis, 1/2000 to 1/200 mg. 



Lipovaccines. Recently LeMoignic and Sezary showed that it is 

 possible to obtain as highly hemolytic serum by injecting red cells sus- 

 pended in oil as by injecting them suspended in salt solution. They also 

 showed that the oil suspension gives slow absorption, and that the oil acts 

 as a detoxifying agent. As an example of the rate of absorption it was 

 shown that the injection 0.35 mgm. of strychnine in aqueous solution 

 kills a guinea-pig, but the injection of six times that amount is harmless 

 if the strychnine be dissolved in oil. This led LeMoignic and Pinoy, 

 Achard and Foix, and LeMoignic and Sezary to suspend bacterial 

 vaccines in oil, and to inject the entire vaccinating dose at one time. 

 Bacterial vaccines suspended in saline are rapidly autolized. As 

 autolysis advances, absorption following injection becomes more rapid 

 and the immediate reaction more severe. Oil vaccines are preserved 

 much more easily than saline vaccines and the reactions following 

 their injection are less severe. The oil vaccines are known as " lipo- 

 vaccines." The bacteria have been suspended in lanolin, lecithin, 

 sperm oil and many vegetable oils. Cotton-seed oil is at present widely 

 used. It is of great importance to use neutral oils. The sterilization 

 of these oils has been a difficult problem and a drawback in the prepara- 

 tion of the vaccines. The technic must be strictly aseptic. At present 

 lanolin and oils are sterilized in the autoclave at fifteen pounds for 



