IMMUNOLOGY. IMMUNITY AND IMMUNIZING AGENTS 251 



have an injurious effect upon the white blood corpuscles, inhibiting leu- 

 cocytosis (negative chemo taxis). If virulent cultures of the bacillus of 

 anthrax are injected into susceptible animals, they succumb quickly- with- 

 out any evidence of leucocytosis (negative chemotaxis). If the animal 

 thus injected had been immunized against anthrax by means of atten- 

 uated anthrax cultures, there would appear large numbers of leucocytes 

 at the site of the injection. If tetanus bacilli and their spores are washed 

 free from toxin and injected, active leucocytoses follows (positive chemo- 

 taxis). The interesting observation has been made that the injection of 

 a mixed culture of highly virulent organisms and non-virulent cultures 

 (of the same kind), the action of the virulent form is both hastened and 

 increased. It is suggested in explanation that the leucocytes preferably 

 seize upon the non- virulent forms and have as a result little energy left 

 to seize upon the virulent forms. 



Toxins, therefore, are intimately concerned in the processes of immuni- 

 zation. They induce the development of anti-bodies which overcome 

 or neutralize the very substances -elaborated by the pathogenic bacteria 

 and they have a markedly checking, retarding or inhibiting in- 

 fluence on leucocytosis. This apparently contradictory action of toxins 

 is not as yet; satisfactorily explained. Metchnikoff suggested that immune 

 bodies as well as complement were enzyma tic in nature and that both were 

 produced by the leucocytes, thus doing away with the necessity for assum- 

 ing that the immune bodies, (anti-bodies), were the result of the action of 

 the toxins or antigens. However, it cannot be denied that the anti-bodies 

 are the result of the presence and influence of the antigens or toxins. 



The toxins or poisons elaborated by certain animals, as poisonous 

 snakes, resemble the antigens of bacteria in that they are capable of 

 inducing the formation of anti-bodies. The following animal anti- 

 toxins are now on the market: Antivenene for rattlesnake poisoning, 

 anti- toxin for scorpion poisoning; and anti- toxins for eel, fish, turtle, wasp 

 and salamander poisons. Most of the animal toxins are not of a simple 

 molecular structure. The toxin molecule of rattlesnake venom, for 

 example, has a distinct toxophore group which give rise to the general toxic 

 symptoms, and a hemolytic group which disintegrates the red blood cor- 

 puscles, and the two act quite independently of each other. 



True toxins are formed by certain higher plants, as ricin by the caster 

 bean plant, crotin by the croton bean plant, robin by the locust, abrin by 

 the jequerity bean plant, and pollenin by certain members of the composite 

 family (golden rods, rag weeds, and others). These several toxins when 

 introduced into the body will give rise to anti-bodies which are used to 

 overcome or neutralize the specific toxins (anti-ricin, anti-abrin, anti-robin, 

 anti-crotin, and anti-pollenin). 



