232 PASSIVE IMMUNIZATION 



guardians of young children, and of those who are so situated that 

 they cannot look after themselves. Of physicians, we may hope, 

 there are none who at the present day would withhold from their 

 patients what the scientific world has come to recognize as the most 

 potent and important curative agent in the management of the 

 disease in question. If, by any chance, however, there should be 

 such a person, then the laity should realize that the non-use of 

 diphtheria antitoxin, in the absence of special indications to the 

 contrary, constitutes sufficient evidence of inefficiency on the part 

 of the practitioner to warrant his prosecution in the courts. 



Preparation of Diphtheria Antitoxin. While the earliest attempts 

 at immunization were made with the serum of some of the smaller 

 laboratory animals (sheep and goats), it soon became apparent that 

 from such sources a sufficient supply could not conveniently be 

 secured, and at the present time the horse is universally employed 

 as antitoxin producer. 



The animals which are chosen for this purpose are first tested 

 with tuberculin and mallein for freedom from tuberculosis and 

 glanders, and, further, receive an injection of tetanus antitoxin to 

 counteract any accidental infection of this kind which might acci- 

 dentally occur during the period of time that the animals are fur- 

 nishing antitoxin. They are well fed and groomed, and every effort 

 in short made to maintain them in the best condition possible. 



For purposes of immunization the toxin furnished by a special 

 strain of the diphtheria bacillus is now r used the world over. This 

 strain has been studied with special care by Park and Williams 

 (New York), whose names it bears, and is grown in 2 per cent, 

 peptone nutrient bouillon of an alkalinity corresponding to 8 c.c. 

 of normal soda solution per liter (above the neutral point to litmus), 

 the broth being beef-broth, and the peptone the usual preparation 

 of Witte. This medium is placed in comparatively thin layers in 

 wide-mouthed Erlemneyer flasks, and kept at a temperature of 

 from 35 to 36 C. At the end of a week the toxin production has 

 reached its maximal point, when the cultures are tested in reference 

 to their purity, and are killed off by the addition of 10 per cent, of 

 a 5 per cent, solution of carbolic acid. After standing for forty- 

 eight hours most of the bacilli have settled to the bottom; the clear, 

 supernatant fluid is filtered through sterile filter paper and is stored 

 in full bottles in the refrigerator. Before use it is tested on guinea- 



