386 Chapter XII 



toxin by certain parts of the brain and the cord. Are we justified in 

 regarding this as comparable to the more stable fixation observed 

 in living animals susceptible to tetanus intoxication? Soon after 

 Wassermann and Takaki's discovery I pointed out that the pounded 

 brain of frogs mixed with tetanus toxin does not prevent animals, 

 into which this mixture is injected, from contracting fatal tetanus. 

 This observation was confirmed by Courmont and Doyon^ in several 

 series of experiments carried out under various conditions. They 

 found that " the brain of the frog, heated or unheated, when mixed 

 with tetanus toxin even for several hours, at the temperature of the 

 laboratory or at 38° C, even in considerable doses, does not possess 

 any neutralising property." This fact would not be in any way 

 wonderful if we had to do with an animal insusceptible to tetanus ; 

 but in the frog, as we have said in the preceding chapter, this is far 

 from being the case. In the cold it does not readily become tetanic, 

 but above 25° — 30° C. it becomes very susceptible. The turtle, which 

 is very refractory to this intoxication, has a brain which, when pounded 

 and mixed with tetanus toxin, exerts a certain preventive power over 

 susceptible animals. Nevertheless, the brain of the living frog, as 

 demonstrated by Morgenroth, absorbs this toxin. There is, therefore, 

 a difierence between the absorption of the tetanus poison by the 

 living elements and by the pounded cerebral substance. A similar 

 result is obtained with several other toxins. Diphtheria poison is 

 very toxic when injected directly into the brain of the guinea-pig or 

 rabbit. Even the rat, as demonstrated by Roux and BorreP, is readily 

 afiected by this toxin under these conditions. Doses which when 

 inoculated subcutaneously are well borne by the rat, when introduced 

 into the brain set up a fatal intoxication in this animal. And yet the 

 [406] brain, when pounded and mixed with diphtheria toxin, can never 

 protect susceptible animals from intoxication. Numerous attempts to 

 reproduce Wassermann and Takaki's experiment with the diphtheria 

 poison have always been unsuccessful. Attempts to obtain the same 

 result with snake venom have also given negative results. Calmette^ 

 made several experiments with emulsions of rabbit's brain and snake 

 venom with the object of ascertaining whether the elements of the 

 nervous system possess against venom the same properties as against 

 tetanus toxin. ^'None of these emulsions" — concludes Calmette — 

 " exhibited either the slightest protective or antitoxic power in vitro, 



1 Compt. rend. Soc. de hiol, Paris, 1898, p. 602. 

 * Ann. de VInst. Pasteur, Paris, 1898, t. xii, p. 238. ^ jc, p. 343. 



