34O BACTERIOLOGY. 



may be questioned, as in the case of the anti- 

 toxin, whether the bactericidal substances of 

 the serum are compounds of the bacterial cell 

 substances with the active body proteids, or 

 whether they are simply body proteids. On 

 the first supposition, it might be expected that 

 any newly-formed compound would, because of 

 its recent origin, be especially reactive and 

 able to act as an intense stimulus to the body 

 cells. The appearance in this case of peculiar 

 bactericidal and antitoxic substances would 

 be only apparently traceable to the emergence 

 of new qualities, to the creation of " specific " 

 substances. The hypothesis might rather be 

 held that, through the action of a chemical 

 stimulus especially appropriate on account of 

 its greater reactivity, what happens is merely 

 that a larger quantity of the same bactericidal 

 or antitoxic substance already present makes 

 its appearance in the blood of immunized ani- 

 mals, and that a normal animal in a healthy 

 condition already possesses the substance as a 

 means of defense, but in a smaller amount. 

 In spite of the proof that elements of " spe- 

 cific " microbes are concerned in the produc- 

 tion of the antitoxins or germicidal substances 

 found in the blood of animals " specifically " 

 immunized or made tolerant of poison, it is 

 very probable that these " specific " bacterial 



