162 H. R. Seddon: 



slight symptoms, and it is noteworthy that with it the initial in- 

 jections were very much smaller. 



In determining the potency of the toxins employed, the minimal 

 lethal dose (m.l.d.) has been interpreted as the smallest quantity 

 which, administered subcutaneously to a 350 grm. guinea pig, has led 

 to death in less than 48 hours. 



The following toxin-antitoxin experiments were performed with 

 the serum from one of these guinea pigs (No. 72). The initial dose, 

 for this guinea pig was l/30th m.l.d. of ^heated toxin (potency de- 

 termined after heating) ; nine injections of heated toxin were given,, 

 after which the animal received six injections of non-heated toxin; 

 the last injection, nine days before bleeding, was 40 m.l.d. This 

 guinea pig showed symptoms of paralysis after the third injection 

 (1/lOth m.l.d.) in consequence of which treatment was suspended 

 for nearly four months; no symptoms have been shown following the 

 subsequent injections, and at time of killing the animal weighed 

 900 grms. and was in excellent condition. 



In order that cross-immunity experiments might be carried out 

 a polyvalent Botulinus antitoxin has been prepared in a cow (Cow 6) 

 by repeated injection of cultures of both type of B. iotulinus. The 

 strains used were " B. botulinus Al " obtained from the Lister In- 

 stitute, through the courtesy of the Director, Dr. C. J. Martin, and 

 " B. botulinus, Type B-, No. 40 " from Dr. K. F. Meyer's collection, 

 kindly supplied by Dr. Hilda Hempl Heller. 



Toxin-Antitoxin Experiments. 



In the following experiment guinea pigs of 225 to 270 grms. weight 

 were used, and the test was carried out as follows: — The toxin-anti- 



Guinea 



Pig-. Antitoxin. 



Toxin. 



Result. 



336 - 



- Parabotulinus 0*2 cc. 



- Parabotulinus 50 m.l.d. 



- Lived. 



338 - 



- Parabotulinus 02 cc. 



- Botulinus A, m.l.d. 



- Died second day. 



340 - 



- Parabotulinus 2 cc. 



- Botulinus B, 1 m.l.d. 



- Died third day. 



337 - 



- No antitoxin 



- Parabotulinus 1 m.l.d. 



- Died second day. 



339 - 



- No antitoxin 



- Botulinus A, 1 m.l.d. 



- Died second day. 



341 - 



- No antitoxin 



- Botulinus B, 1 m.l.d, 



- Died third day. 



342 - 



- Botulinus 1 cc. - 



- Parabotulinus 1 m.l.d 



- Died in 20^ hours. 



344 - 



- Botulinus 1 cc. 



- Botulihus A, 2 m.l.d. 



- Lived. 



346 - 



- Botulinus 1 cc. 



- Botulinus B, 2 m.l.d. 



- Lived. 



345 - 



- Botulinus 1 cc. - 



- Botulinus A, 5 m.l.d. 



- Lived. 



347 - 



- Botulinus 1 cc. 



- Botulinus B, 50 m.l.d. 



- Lived. 



343 - 



- Serum normal guinea 







pig 



- Parabotulinus 1 m.l.d. 



- Died in 22 hours. 



Antitoxins. — Parabotulinus, Serum G.p. 72. 



Botulinus (polyvalent), Serum of Cow 6, 13/9/22. 

 Toixins.— B. parabotulinus of 11/9/22. M.l.d. 0'004 cc. 



B. botulinus Type A., Al of 30/9/22. M.l.d., 1 cc. 



B. botulinus, Type B., B-40 of 21/7/22. M.l.d, O'Ol cc. 



