576 MICROBIOLOGY OF SPECIAL INDUSTRIES 



white scours of calves, sheeppox, foot-and-mouth disease, canine dis- 

 temper, rinderpest and spotted fever. The action of this group is 

 directed more especially against the specific microorganisms involved, 

 resulting in dissolution of the cells or lysis due to lytic bodies in the 

 antisera (bacteriolysins). 



In addition to the presence of lysiris in antimicrobial serums, other 

 antisubstances are known to exist, as agglutinins, bacteriotropins 

 (opsonins), and precipitins. The antibody content of antimicrobial 

 serums is comparatively httlg understood and the clinical interpreta- 

 tion of lysins, agglutinins and precipitins is not clear. 



Antitoxic Serums 



Diphtheria Antitoxin. — A culture of the organism may readily be 

 secured from the throat of a patient by transferring some of the diph- 

 theritic exudate, on a sterile cotton swab, to Loeffler's blood-serum 

 culture medium. After the growth of the bacteria at incubator tem- 

 perature, contaminating organisms may conveniently be eliminated by 

 the inoculation of a guinea-pig and the isolation of the diphtheria organ- 

 isms from the tissues. ,A pure culture is necessary in the preparation 

 of the antitoxin, but any given culture should not be reUed upon until 

 tests have been made of the final product. 



To produce the diphtheria toxin with which the antitoxin horses are 

 treated, the diphtheria organisrhs, in pure culture, are transferred to 

 beef broth, contained in large flasks, and intubated at a temperature of 

 37°. A rapid growth takes place, during which the specific toxin is 

 elaborated by the organisms. After a period of incubation of about 

 two weeks, the bouillon culture is removed from the incubator, examined 

 microscopically in order to make sure that contamination is not present, 

 a preservative is added, usually carbolic acid, trikresol, or purified cre- 

 sols, and the organisms are removed from the culture by passing the 

 liquid through a Berkefeld filter. The filtrate (diphtheria toxin) is 

 then placed in the refrigerator until used. 



The horses which are used in the manufacture of antidiphtheritic 

 serum, as well as for the preparation of other antiserums, must be 

 submitted to rigid inspection before being placed on the treatment. 

 These animals, when purchased, are placed in a detention stable for 

 several weeks. During this time they are subjected by a quahfied 



