156 IMMUNIZATION 



time was 10 days, i.e. about the same. The good 

 agreement of the calculated figures with the observed 

 ones during the periods of rapid increase and of 

 regular decrease are strongly pronounced. 



In another experiment Madsen and Jorgensen 

 injected 20 cc. of a culture of typhoid bacilli sub- 

 cutaneously into a goat which had not been treated 

 before. The time of incubation with absence of 

 agglutinin lasted for 55 days and was much longer 

 than in the two last cases, when the animals had 

 been injected with the same bacilli before. The 

 time of rapid increase for about nine days showed 

 an enormous production of agglutinin — about 2000 

 units a day. The observations of the regular 

 decrease are very few (only three). They seem 

 to indicate a sinking to the half-value in about five 

 days, i.e. about double as rapidly as in the goats 

 which had been immunized before. 



A special case of active immunization, in which 

 till now only the period of regular slow decrease has 

 been observed, concerns the content of agglutinins 

 in the blood of persons who have been attacked by 

 bacterial diseases. In such cases it is often found 

 that the slow decrease goes on much more slowly in 

 the latter part of the observed period than in the 

 first time. As instances I give two series, the one of 

 Jorgensen regarding the content of typhoid agglutinin 

 in a patient's blood after typhoid fever, the other of 

 Sir Almroth Wright regarding agglutinin specific 

 against the bacillus causing Malta fever. 



