TOXINS. 177 



The incubation period may be shortened experi- 

 mentally by the injection of large quantities of 

 toxin, but it can not be eliminated entirely. The 

 poisons of snake venoms appear to act without in- 

 cubation period, but they are still to be classed 

 with the toxins, because of their power to cause 

 the formation of antitoxins. 



6. "The facts make it necessary to assume, as a 

 condition for the poisonous action of toxins, a spe- 

 cific chemical union of the toxin with the proto- 

 plasm of the cells in certain organs." . . . "The 

 affinity of other poisons, as the alkaloids, for 

 tissues, depends not on chemical union, but on 

 some such process as solid solution or loose salt 

 formation." 



The preparation of the soluble toxins of bacteria Preparatioi 

 is relatively simple. It is necessary only to inocu- 

 late a suitable fluid medium with a culture of the 

 microorganism, to allow growth to take place for 

 some days at body temperature, then to pass the 

 fluid through a porcelain or some equivalent filter. 

 The soluble toxins usually may be precipitated 

 from the filtrate by some precipitant, as ammon- 

 ium sulphate, and preserved in a dried state for a 

 long period. Such a precipitate does not represent 

 the toxin in a pure form, but various proteid sub- 

 stances of the culture medium, as well. 



The bacilli of diphtheria and tetanus, Bacillus 

 pyocyaneus, and Bacillus lotulinus, are the princi- 

 pal micro-organisms which produce soluble toxins. 



When the toxins of these organisms are injected 

 into a suitable animal, phenomena similar to those 

 produced by an infection with the organisms 

 themselves are produced. They are in a particu- 



