VIII 



again. The maximum of production occurs 2 3 days 

 before the acme of the curve is reached. The produc- 

 tion of antibody, to which the injected culture (or toxin) 

 has given rise, ceases at the time when the curve has 

 reached the acme, or is continued to a small extent for 

 a short time after this point has been reached. The anti- 

 body present then decreases accordingly to quite a simi- 

 lar law, as would be the case if it was a foreign anti- 

 body, injected into the blood. 



It is therefore easy to understand, why a regular 

 immunisation will give much belter results, when the 

 injections of toxin are given every third day, (as first 

 pointed out by Dean 1 ), instead of the day, on which 

 the acme is supposed to occur 2 ). The period of pro- 

 duction, on an average 9 days, can approximately be 

 divided into three periods: 3 days of incubation, there- 

 after 3 4 days to the maximum of production and at 

 last 2 3 days to the end of it. Thus an injection given 

 3 days after another, will have its maximal production 

 at the time, when the effect of the first has ceased. In 

 this way no interruption in the increase of the anti- 

 body will take place. If the injection is given on the 

 day of the acme, 6 days or so will pass before the maxi- 

 mum of production is reached and during those 6 days 

 a considerable loss of antibody incurs. 



During the second phase the increase, due to the 

 production of antibody, is counteracted by the decrease 

 according to the law mentioned. This decrease at last 

 predominates. These phenomena might be compared 



1) George Dean: Problems of diphtheria immunity. Transact, of the Pathol. Soc. of 

 London 51. I. 1900. 



2 ) Brieger und Ehrlich: Beitriige zur Kenntniss der Milch immunisierter Thiere. 

 Zeitschr. f. Hyg. XII. 1893. 



Salomonsen og Madsen: Recherches sur la marche de 1'immunisation active 

 centre la diphtheric. Ann. de 1'Inst. Pasteur 1897. 



11 



