PRODUCTION OF TETANUS TOXIN 417 



greater differences. The average toxicity in this period of 1918 

 was 1:6,500. In the year 1919 this quarter gave a high aver- 

 age toxicity of 1:60,000 and the same period in the year 1910 

 showed an average toxicity of 1 : 14,000. 



SUMMARY 



In going over the above results, it will be seen that Witte 

 pepton has been an important factor in the production of a fairly 

 constant potent tetanus toxin. The indications are that the 

 Berna pepton is a satisfactory substitute for Witte. since the 

 latter is no longer available. 



It would seem either that the Swiss Serum and Vaccine Com- 

 pany was justified in its claim that Berna pepton was made 

 according to Witte formula or that Berna pepton was in reality 

 Witte pepton since only when using these two peptons did we 

 obtain a toxicity of 1 : 100,000. 



It was a great disappointment that Martin pepton broth as 

 made by us proved so unreliable. It is just possible that one of 

 the reasons for the better results with this broth at the Pasteur 

 Institute, is due to the fact that a larger number of stomachs 

 are used for the preparation of the pepton than we can handle at 

 one time at the Bureau of Laboratories. 



