IMMUNITY, IMMUNIZATION, AND CURE. 73 



Recent experiments of Donitz with tetanus-antitoxin 

 show, further, in a most conclusive manner, that the amount 

 of serum necessary for curative purposes is the greater the 

 longer the period of time that has elapsed between the in- 

 toxication and the institution of serum-therapy. Eight 

 minutes after tetanus-intoxication, according to Donitz, six 

 times as much serum is required in order to save the 

 animal as when the serum is injected immediately after the 

 poison ; after an hour the curative dose is twenty-four 

 times the original dose ; and so on, until finally a period 

 is reached at which it is entirely impossible to save the 

 animal, even with the largest amount of the most active 

 serum. For this reason it is, above all things, essential in 

 obtaining serum for therapeutic purposes to establish in 

 the animals yielding the blood (generally horses) as high 

 a degree of immunity as possible. The higher the degree 

 of immunization established, the smaller the amount of 

 serum required to effect cure. In making the degree of 

 immunity as high as possible it must be borne in mind that 

 the immunizing process pursues a wave-like course (Brieger 

 and Ehrlich). Immediately after introduction of the next 

 higher toxic dose the immunizing power of the blood-serum 

 diminishes. It remains for a few days at the lower level, 

 gradually rising again until it reaches the maximum. From 

 this point it sinks again, and it finally reaches a level at 

 which it persists for weeks. The most favorable time for 

 injecting new toxin into the animals in order further to 

 fortify their immunity is when the strength of the serum is 

 highest that is, when the anti-bodies are present in the 

 body in largest number. 



The efforts in the domain of curative serum-therapy have 

 already yielded material practical results in the case of 

 diphtheria. In that of tetanus success is as yet doubtful. 

 We shall refer fully in the special section in the discussion 

 of these two diseases to the mode of obtaining and of esti- 

 mating and to the dosage of the curative serum. 



Naturally, immunization is not the only manner in which 

 therapeutic attack upon bacterial diseases is to be made. 

 An infectious disease may be terminated by reason of the 

 death of the bacteria in the body. It would be possible to 

 effect cure in this way if the infectious agent could be de- 

 stroyed within the body by means of internal disinfection. 

 In spite of the large number of antiseptics at our command, 



