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MASS. EXPERIMENT STATION BULLETIN 267 



vaccine was added to each tube of cooled, melted sugar for plating and one 

 loopful of vaccine thoroughly streaked over each agar slant. They were in- 

 cubated for 24 hours, after which the number of colonies were counted. The 

 Wolfhiigel plate and mathematical computation were used when needed to 

 count the plates. The respective averages of the four plates and four slants 

 were computed and recorded as shown in the following table. 



Table 4. — Action of Glj'cerol Content of the Diluent on the 

 Contaminating Organisms in the Cutaneous Vaccine. 



Interpretation. — A comparison of the control and standard vaccine plates 

 in Table 4 shows that the glycerol content of the standard vaccine had a 

 decided inhibiting and disinfecting action on the contaminating organisms in 

 the vaccine. A comparison of .slants shows a similar result. At the end of 

 707 hours the standard vaccine was nearly sterile asi far as contaminating 

 organisms were concerned. This near sterility was first noticeable at 423 

 hours. This is comparable with the attenuation of the vaccine, as described, 

 which was marked when it was older than 25 days (600) hours. 



A repetition of this experiment gave comparable results. The average 



