THE TOXINS 159 



broth-cultures. It is necessary to destroy the cell to set free 

 the poison. The process may be exemplified by the zymase 

 production of Ed. Buchner, in which the yeast cell is ground 

 up and expressed. 



3. A special group has to be made for the poison of the 

 tubercle bacillus (tuberculin), and that of the bacillus of 

 glanders (mallein). These diffuse into the broth, but there 

 remains some in the substance of the bacterium ; hence the 

 bodies of tubercle bacilli form an active tuberculin. 



Besides the specific toxins, cultures may contain non-specific 

 poisons, the proteins of Buchner. 



Soluble toxins. — The toxins of diphtheria, of tetanus, and of 

 botulismus are known (the latter being produced by an 

 anaerobic bacillus growing in meat). They can be obtained by 

 cultivating the bacteria with an abundant supply of air (in the 

 case of the bacillus of diphtheria), or in broth deprived of 

 oxygen (in the case of the tetanus bacillus). The bacteria are 

 removed from the fluid by filtering through porcelain bougies. 

 Those strains of bacilli are picked out which furnish the best 

 toxins, for good toxins are necessary for the production of 

 good antitoxins. 



The Characters of the Soluble Toxins. — The soluble 

 toxins possess very definite characters ; in the first place they 

 are strictly specific ; the symptoms produced by the diphtheria 

 toxin are quite distinct from the symptoms of tetanus. Their 

 action is specific in another sense, as it varies in the different 

 animal species. The fowl does not react to the tetanus toxin 

 as does the mouse or the human subject. Secondly, they are 

 extremely potent : a good culture of tetanus can kill the 

 mouse in a dose of y^jjj^j- cm. The diphtheria toxin kills 

 a guinea-pig of 250 grams in a dose of xTnnr ^-^-^ The 



^ " I c.c. of the active fluid toxin produces on evaporation in vacuo o'oi 

 gram of dry residue. Deducting the weight of ash and the portion in- 

 soluble in alcohol (which has no toxic activity) there remains 0*0004 gram 

 of organic matter. It is certain that the greater portion of this weight 

 consists of substances other than the diphtheria toxin. Yet this minute 

 quantity is sufficient to kill at least eight guinea-pigs of 600 grams each, 

 or two rabbits of 3 kil. " ( Roux and Yersin. ) — i c. c. of a good tetanus 

 filtrate dried in vacuo leaves o'04 gram of dried residue of which 0*025 



