462 PRINCIPLES OF VETERINARY SURGERY 



develop. Antitoxic injection made before the tetanic infec- 

 tion enables animals to resist the disease with absolute cer- 

 tainty. The serum confers the g-enuine immunity, and the 

 immunity is acquired immediately after the introduction of 

 the serum into the animal. It is proportionate to the dose, 

 and is very different from the slow, lasting immunity ac- 

 quired through iodated or heated toxins. 



Antitoxic Immunity is Immediate but Transient. — It is 

 incapable of curing or attenuating tetanus that has once de- 

 veloped. It may interfere with free toxin in the organism 

 or with that produced at the tetanic focus, but is ineffectual 

 aganst the toxin that has been absorbed and fixed by the 

 nerve cells. 



Tetanic antitoxin is precipitated from the serum by alco- 

 hol, magnesia sulphate and tannin. It is altered by heat, 

 passes readily into the dialyzer, and can be preserved in the 

 dry state. 



Whether the antitoxin is the. result of transformation of 

 the toxin or is elaborated by the cells is a question. It seems 

 possible that it is the product of cellular secretion, probably 

 of the leucocytes. Vaillard bled an immunized rabbit, white, 

 again and again, and found its serum was always antitoxic. 

 We must needs conclude that the antitoxin carried ofT with 

 each bleeding was replaced. 



The antitoxic activity of the serum and the immunity do 

 not go hand in hand. Vaillard succeeded in immunizing a 

 rabbit without its serum becoming antitoxic. He inoculated 

 the animal in the tail with spores and lactic acid two or 

 three times, in small doses. The rabbit afterward resisted 

 toxin and bacilli mixed with favoring micro-organisms and 

 yet its serum was not antitoxic. Furthermore, animals that 

 have been immunized and kept for a long time lose their an- 

 titoxic power. If at a given moment they are again injected 

 with to.xin they will be found to resist it quite as well as 



