410 HARRIET LESLIE WILCOX 



occurred in the first, third and fourth quarters, while the second 

 quarter gave an average toxicity of 1 : 27,000. 



The differences in the quarterly averages of the year 1916 

 were so slight that they were scarcely worth mentioning. The 

 third quarter in this period showed the lowest average toxicity of 

 1:20,000 while the first, second and fourth quarters gave an 

 average toxicity of 1:22,000. 



Doubtless if Witte pepton veal broth had been used through- 

 out the year 1917 we should have had a greater variation in the 

 quarterly averages, due to the two extremely potent toxins pro- 

 duced in the third quarter. As far as was known no especial care 

 was taken in the preparation of these two broths nor in the filtra- 

 tion of these toxins. In lot 127, the usual procedure of testing 

 for 1 : 15,000 and 1 : 25,000 was carried out. When the pigs suc- 

 cumbed in less than forty-eight hours, higher tests, namely 

 1:40,000 and 1:60,000 were made with similar results. Dilu- 

 tions of 1:80,000 and 1:100,000 were then injected into guinea 

 pigs weighing 350 grams each. The pig receiving the 1:80,000 

 dilution died between the second and third day, while the pig 

 which received the 1:100,000 dilution succumbed on the fourth 

 day. Since this was the strongest toxin ever obtained at the 

 Bureau of Laboratories, tests were made of the toxin filtrate to 

 preclude any possibility of spores or bacilli having passed through 

 the Berkefeld filter. These tests were negative. 



DIFFERENT PEPTONS 



In the spring of 1916, we anticipated the present shortage of 

 Witte pepton and made comparative tests with some of the 

 domestic peptons on the market. These results are to be re- 

 garded as comparative only, but in those that were controlled 

 by the use of Witte pepton, the differences in the toxicity, with 

 one or two exceptions, were very significant. 



A subsequent test, made with another preparation of Fair- 

 child pepton, gave a toxicity of only 1:8000. No control test 

 was made as "we were unable to obtain Witte pepton. 



