ACTION OF DIPHTHERIA TOXIN 75 



show only slight tendencies to toxin formation, a virulent toxin may ne- 

 cessitate a special strain of the bacterium. 



The length of time required by cultures for the production of moderate 

 amounts of toxins is by no means constant. With diphtheria this varies 

 from several days to 2 to 3 weeks. As a general rule, if toxin is not 

 liberated within the first four weeks it will most probably not appear 

 after that time. It is isolated by filtering the bouillon culture first 

 through filter paper to remove the pellicle, and then through a bacterial 

 filter to get rid of the bacteria. A layer of toluol i to 2 cm. is added 

 for the purposes of sterilization and it is advisable to agitate the toxin 

 and toluol thoroughly every day to prevent contamination. 



It does not fall within the scope of this book to take up the various 

 methods proposed for obtaining and preserving the various toxins. It is 

 the object merely to review the details associated with their mode of 

 action and standardization. 



The first and most important member of this group is the diphtheria 

 toxin. 



The diphtheria toxin is first tested by subcutaneous injections into 

 Action of guinea-pigs 250 gms. in weight. The action of the toxin is entirely de- 

 Diphtheria pendent upon the dosage; the more toxin injected the more rapidly does 



Toxin. death occur. This, however, is not to be taken in mathematically correct 

 proportions i.e., twice the dose does not produce the same action in 

 one-half the time. A certain period of time must always elapse before death can take place, 

 the minimum being about one day. This interim is known as the period of incubation 

 and it is the existence of this that goes to make one of the essential characteristics of a 

 true toxin. A toxin requires a definite period of time for its action to become manifest; 

 and even the largest dose of toxin cannot diminish the length of this period below a certain 

 minimum. On the other hand, the length of the incubation time can be increased by 

 the injection of a smaller dose, so that ultimately a dose small enough is obtained which 

 is not instrumental in producing death (Dosis subletalis). 



If a guinea-pig is inoculated with a quantity of toxin sufficient to kill it in three to 

 four days, nothing abnormal is evident the first day ; various manifestations of illness, 

 however, follow soon after. 



Edema appears at the site of inoculation. The animal stops eating, sits in a corner, 

 and reacts poorly to sound. Gradually it becomes weaker, so that when placed upon 

 its back it does not resume its normal position; the temperature which at first rose some- 

 what, falls abruptly and then death takes place. 



At autopsy, a gelatinous and strongly hemorrhagic edema is found which starts at 

 the site of the injection. On opening the abdominal cavity one finds but very little 

 peritoneal exudate, strongly injected vessels of the mesentery, and especially charac- 

 teristic, markedly reddened adrenal glands. In the thorax are found bloody pericar- 

 dial and pleural exudates, and consolidated areas in the lungs. 



After the injection of smaller doses, edema likewise arises and becomes larger in 

 extent the slower the case progresses. Besides this, the animal loses in weight. With 

 sublethal doses, edema or infiltration is confined to the site of injection, and finally, 

 with the minutest doses, no edema occurs, but the hair falls out at the place of 

 injection. 



