160 H, R, Seddon: 



In the case of cattle, it would appear that B. parabotulinus is the 

 common cause and not B. botwlinus, for though the toxin of this latter 

 organism is capable of inducing symptoms of Bulbar Paralysis, it 

 has been shown by Hart and Hayes^ that the ox is relatively insus- 

 ceptible, the administration of massive doses of toxin being necessary 

 to cause symptoms. 



In order therefore to determine definitely the relationship of 

 B. parabotulinus to B. hotulinus, investigations have been continued 

 and the results of toxin-antitoxin tests are given below, together 

 with a short summary of the other points of difference between these 

 two organisms. 



Comparison of B. botulinus (Types A and B) and 

 B. parabotulinus. 



(a) Morphological and cultural characters. 



In the earlier paper it was pointed out that while the two types 

 -of B. botulinus were identical morphologically and culturally (as is 

 well known), B. paral)otulinus showed certain differences in that (1) 

 it was distinctly larger, (2) it formed a wholly branched colony in 

 solid media, and (3) it failed to show gas formation in glucose media. 

 It was upon these grounds that the organism isolated here was 

 -differentiated from B. botulinus. 



(b) Toxin formation. 



As is well-known, Types A. and B. of B. hotulinus, both produce 

 powerful toxins, and these toxins are identical in that they both 

 give rise to the same symptoms, but, as has been pointed out by 

 Grahams whereas Type A is highly fatal for chickens (in which it 

 induces Limberneck), Type B. toxin is not. Further it was pointed 

 out many years ago by Leuchs, and has been confirmed by others, that 

 the anti-toxin to one type does not protect against the toxin of 

 the other type, and vice versa. 



The bacteria-free filtrates of cultures of B. parabotulinus likewise 

 induce symptoms identical with those due to botulinus toxin, and, 

 though exact determinations of relative susceptibility have not been 

 made, it has further been shown that cattle and horses possess much 

 the same susceptibility to these filtrates of B. parabotulinus (whereas 

 Hart and Hayes* have shown that such is not the case with 

 botulinus toxin). The administration of parabotulinus filtrates to 

 chickens in such experiments as have been as yet performed, indicates 

 their behaviour to be similar to that of the toxin of Type B. 

 B. botulinus. 



Further work has led to the production of much more powerful 

 filtrates of B. parabotulinus than those previously recorded, e.g., of 

 one product subcutaneous injection into a guinea pig at the rate of 



2. aroiurnal of the American Veterinary Medical Agaociation, Tol, 57 

 •(10), 1920, p. 638. 



3. Journal of Infectious Diseases, Vol. 28, 1921, 317. 



4. loc. cit. 



