THE MICROBIAL TOXINS. 83 



alterable by heat, and the reactions of which 

 entitle it to be considered as a nucleo-albumin ; he 

 has also found in it a toxic nuclein. 



These toxic substances are found, according to 

 Gamaleia, Pfeiffer, and Sanarelli,* confined during 

 the life of the microbe within its cellular envelope, 

 and does not diffuse through this. Metchnikoff 

 and Rotix are of the contrary opinion,! however 

 and they have prepared a toxin almost insensitive 

 to a temperature of 100° C, and precipitable from 

 its solutions by ammonium sulphate or strong 

 alcohol; the toxin is a toxalbumin. This toxin is 

 quite toxic ; one-third of a cubic centimeter suffices 

 to kill 100 Gm. of guinea-pig in 18 hours ; with larger 

 doses, death is almost immediate. 



By immunizing guinea-pigs, rabbits, and horses 

 with this cholera toxin, Metchnikoff and Roux 

 obtained a serum which is distinctly antitoxic for 

 rabbits. Nothing absolutely certain has been found 

 as to its action on man. J 



We will not dwell longer here on the toxins of 

 microbial origin. It appears evident, however, 

 from what has been stated above, that the great 



* Annal. de I'Instit. Pasteur, ix, p. 129. 



t Ibid., X, p. 257. 



J Haffkine: Compt. rend, de I' Acad, des Sciences, 1892; 

 Metchnikoff: Annal. de I'Instit. Pasteur, vii, p. 403; and 

 Roux: Ibid., x, p. 253. 



