PRINCIPLES OF VETERINARY SURGERY 461 



not found in the coagulum, but is met Avith in the transudate 

 of oedemas and in large quantities in the mill<, to which Ehr- 

 lich attributed the hereditary transmission of the immunity. 

 The saliva, the aqueous humor and the urine may exhibit 

 feeble antitoxic activity. 



PROPERTIES OF ANTITOXIC SERUM.— The. prin- 

 cipal properties of antitetanic serum are already known. 

 Mixed in vitro, with the toxin, it neutralizes the latter, and 

 the action is instantaneous. As soon as the mixture is ef- 

 fected it is harmles,s to animals. When gradually increasing 

 quantities of toxin are poured into a given quantity of anti- 

 toxic serum there arrives a time when the antitoxic activity 

 of the latter is destroyed, and the liquid will give tetanus to 

 animals that receive it. 



It has been thought that the toxin and the antitoxin were 

 capable of uniting into a definite unpathogenic combination, 

 which is, however, not the case, as Roux has shown that the 

 toxin is not destroyed, and that both the toxin and the anti- 

 toxin preserve their specific properties. The injection of the 

 mixture is harmless in the most sensitive animals, only when 

 they have never been subjected to the action of micro-or- 

 ganisms or microbian products. But if the mixture is in- 

 jected under the skin of cavies that have been previously sub- 

 jected to the action of cultures of the bacillus prodigiosus, 

 the streptococcus, the bacillus coli communis, etc., although 

 having all the appearance of health, they die of tetanus. 



The resistance of cavies to a mixture of toxin and anti- 

 toxin serum is not due to the destruction of the toxin, but to 

 the serum exerting a peculiar stimulating influence over the 

 cells to such an extent as to render them capable of resisting 

 the action of the poison. Whatever may be the mechanism 

 of the action of the antitoxic serum, it is none the less true 

 that it is preventive. If injected into an animal at the same 

 time, before or immediately after the toxin, tetanus does not 



