284 AGEICULTUEAL AND INDUSTRIAL BACTEKIOLOGY 



Origin of Antitoxin. — It has already been noted that 

 when a tbxin is injected in sublethal doses into a suitable 

 animal, this animal will react eventually by the develop- 

 ment in its blood serum of substances (called antitoxins) 

 capable of neutralizing toxin of the type injected. Experi- 

 ence has shown that these antitoxins are developed not only 

 in quantities sufficient to neutralize the amount of toxin 

 injected, but quantities greatly in excess of this. It was 

 also noted that toxins poison because of their ability to unite 

 chemically with certain cells of the body and injure them. 

 According to the Ehrlichian conception, when these toxins 

 are not combined with the cells in amount sufficient to cause 

 death of the cells, these cells are stimulated to an excessive 

 production of antitoxins which are thrown off into the 

 blood serum and by combining there with the toxin prevent 

 its union with the cells. It may be emphasized that anti- 

 toxins are specific, that is, each kind of toxin causes the 

 development in the animal's body only of its own particular 

 type of antitoxin and this antitoxin will neutralize only the 

 type of toxin which caused its production. 



Manufacture of Diphtheria Antitoxin. — The blood 

 serum from an animal which has been actively immunized 

 by repeated injections of the toxin of the diphtheria bacillus 

 may be used for the prevention or treatment of diphtheria 

 in man. An account of the method of preparation will 

 serve to show the general principles governing manufacture 

 of antitoxins. Production of antitoxins of other types dif- 

 fers from that described for diphtheria only in details. 



Preparation and Standardization of Toxins. — Inasmuch 

 as the diphtheria toxin is an excretion of the diptheria 

 bacillus it can best be prepared by growing the bacteria in 

 broth and when the toxin formation has reached the maxi- 

 mum the bacteria may be filtered off by means of a porcelain 

 filter. The broth is usually placed in large flat-bottomed 

 flasks, the layer of broth being comparatively thin. The 



