44 COMBINATION OF TOXINS AND TISSUES 



was able to demonstrate the presence of tetanus toxin in the 

 tortoise, which is insusceptible to the action of that substance, 

 at a period of four months after the injection. That the disap- 

 pearance which occurs in susceptible animals is actually due to 

 a combination of the toxin with the tissues of the body, and not 

 to its destruction or elimination, is shown by the fact that the 

 tissus of an animal which has been injected with tetanus toxin, 

 but which no longer contains that substance in the blood, may 

 produce tetanus when injected into a susceptible animal. In the 

 case of fowls it seems that this power of combining with tetanus 

 toxin is most marked in the leucocytes. Again, it is possible 

 to reproduce the absorption of tetanus toxin by fresh tissues in 

 vitro. This has been especially studied by Ignowtowsky, who 

 showed that emulsions of liver, kidney, spleen, etc., have the 

 power to absorb tetanus toxin, but that the subsequent injection 

 of these cells will produce the symptoms of the disease. 



It ought to follow logically that the toxin will combine especially 

 with those cells and tissues which are acted upon by it in the 

 living body, and in all probability this is the case. The proof, 

 however, is somewhat difficult. Wassermann apparently proved 

 the point by his demonstration of the fact that tetanus toxin is 

 absorbed and neutralized by an emulsion of the central nervous 

 system, and not by that of any other organ, although, as has 

 been mentioned above, it is absorbed by other tissues. Now, 

 tetanus toxin acts entirely, or almost entirely, on the central 

 nervous system, and this well-known and oft-quoted experiment 

 appears to constitute a proof of the point at issue. The exact 

 interpretation of Wassermann's experiment appears, however, to 

 be doubtful, and it is hardly safe to rely on it as a proof of the 

 point. 



With the bacterial haemolysins, which, although of feeble 

 toxicity, are in every other respect identical with the exotoxins, 

 we are on surer ground. A filtered broth culture of the tetanus 

 bacillus contains the specific toxin (tetanospasmin), and in addi- 

 tion a second substance, which has the power of dissolving red 

 blood-corpuscles when kept at a temperature near that of the 

 body. At a low temperature they do not act in this way ; but if 

 red corpuscles be added in suitable amount to a solution of tetano- 

 lysin at a temperature of o C. and centrifugalized, the supernatant 

 fluid has no longer the power of producing haemolysis. On the 

 other hand, the red corpuscles, even after washing with normal 



