If Artijicial immunity against toxins 303 



greater degree than do guinea-pigs. The fowl, according to Knorr, 

 develops " a large quantity of antitoxin, whilst the tetanic symptoms 

 are still augmenting." In this animal, as we have been able to show^, 

 a portion of the tetanus toxin is absorbed by the leucocytes. By [413] 

 exciting aseptic exudations in fowls into which I had previously 

 injected this toxin, I was able to convince myself that these exuda- 

 tions, much richer in leucocytes than was the blood, were also much 

 more tetanigenic than was the blood. I observed also a more or 

 less pronounced leucocytosis after the injection of non-lethal doses 

 of tetanus toxin into fowls. It is possible that the leucocytes were 

 actual agents in protecting the animal against the penetration of this 

 poison to the susceptible nerve centres. 



The great susceptibility of leucocytes to microbial toxins serves 

 to indicate that these cells are of some importance in the struggle 

 of the animal against these poisons. Their injection usually sets up 

 a marked hyperleucocytosis of the blood. On this point Chatenay % 

 Avorking in my laboratory, has carried out a series of experiments on 

 animals poisoned by bacterial (tetanus and diphtheria), phanero- 

 gamic (ricin and abrin) and animal (snake venom) toxins. He was 

 able to demonstrate a striking analogy between them and the pheno- 

 mena which occur in bacterial infections. When death takes place 

 at the end of a very short period, the number of leucocytes markedly 

 diminishes ; if the animal lives beyond 24 hours or resists completely, 

 a hyperleucocytosis, often of very marked character, is produced. In 

 the guinea-pig, which is so susceptible to tetanus, the leucocytosis 

 observed occurs even after injections of quantities of tetanus toxin 

 equal to several lethal doses, and it is only after the introduction of 

 an amount equal to one hundred times the lethal dose that the 

 number of leucocytes remains stationary or shows a diminution. 

 Here we have something analogous to what takes place against the 

 anthrax bacillus in the same animal. The penetration of this deadly 

 organism sets up a marked leucocytosis, but the accumulated leuco- 

 cytes are incapable of seizing the bacilli or of preventing their noxious 

 action. In other species of animals, such as the rabbit and the fowl, 

 the intervention of the leucocytes against the anthrax bacillus, as 

 well as against the tetanus toxin, is more effective. 



If this toxin, instead of being injected in solution, be introduced 

 along with the bodies of the micro-organisms which contain it, the 



1 Ann. de VInst. Pasteur, Paris, 1897, t. xi, p. 808. 



2 " Les reactions leucocytaires, vis-a-vis de certaines toxines," Paris, 1894. 



