240 PASSIVE IMMUNIZATION 



antitoxin (for prophylactic purposes). In the animal experiments 

 excellent results have thus been reached. Th. Smith could thus 

 demonstrate that in guinea-pigs the subcutaneous injection of a 

 harmless toxin-antitoxin mixture produces an immunity which extends 

 over several years. Similar results have been obtained by v. Behring, 

 and it would appear from the tests being now made in the human 

 being that the method is thoroughly practical and no doubt will 

 soon be introduced into general practice. In this connection it is 

 interesting to note that the blood-serum of an immunized human being 

 when injected into another individual will bestow a more lasting 

 degree of protection than can be obtained with the use of a heter- 

 ologous serum. 



Centra-indications to the Use of Antitoxin. In view of the fact that 

 a smaller number of people are hypersensitive to the use of horse 

 serum to such a degree that a first injection even may be followed 

 by most alarming symptoms, and in rare instances by death, some 

 physicians have of late hesitated to use antitoxin as promptly as 

 has generally been urged. Should such symptoms develop, it is 

 recommended to administer atropin and adrenalin hypodermically 

 and to resort to artificial respiration. It should be borne in mind, 

 however, that actual disaster is an extreme rarity when compared 

 with the innumerable instances in which antitoxin is used without 

 any untoward results, and that the danger which the unprotected 

 patient incurs from the diphtheria is infinitely larger than that 

 which would likely follow the use of the serum. Unless, therefore, 

 it is known beforehand that the patient is hypersensitive to such an 

 extreme degree, there should be no hesitancy on the part of the 

 physician to use the serum. 



It would, of course, be ideal if some method could be worked 

 out which would enable us to establish definitely the existence of 

 abnormal hypersensitiveness before the injection, but as yet no 

 such method exists. In some instances in which alarming symp- 

 toms followed the injection of the horse serum a history was obtained 

 that the patients had been subject to asthmatic attacks, and in 

 some of these such attacks were brought on when the individual 

 came into close contact with horses. It would accordingly be well 

 to inquire into this point before the injection is given, and possibly 

 to rule out from the treatment all those in whom a distinct history 

 of asthma is obtained. In such cases antitoxin derived from some 



