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 Roux are of the contrary opinion, f 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. 



f Ibid., x, p. 257. 



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

 METCHNIKOFF: Annal. de V Instil. Pasteur, vn, p. 403; and 

 Roux: Ibid., x, p. 253. 



