498 Chapter XV 



[52iJ serum is injected below the skin of persons whom it is wished to 

 protect against the action of the diphtheria bacillus. 



With the object of bringing about a unification of the methods 

 of estimating serums used in difierent countries the International 

 Congress of Hygiene, held at Madrid in 1898, appointed a special 

 Commission to settle this problem. But when the Congress met 

 again at Paris in 1900 this Commission had not completed the task 

 allotted to it. The representatives of the various methods had 

 exchanged ideas, but in applying the same method the results 

 obtained in various places and by various observers presented 

 differences too great to allow of any understanding being arrived at. 

 It is evident that we have here a very complicated problem. The 

 serums are tested on living animals in which of course nothing like 

 the constancy of a chemical reaction can be obtained. 



Possibly the methods of breeding and the races of the same 

 animals in the different countries may be quite sufficient to explain 

 the divergencies in the results obtained. Whatever may be the 

 reason the unification of serum estimation has not yet been obtained, 

 and it is difficult to anticipate that any better result is to be ar- 

 rived at. 



From all this we may draw the conclusion that the possibility 

 of attaining a too rigorous precision in the standardisation of serum 

 has been exaggerated. Our object must be to obtain results as 

 favourable as possible in the application of the antidiphtheria serums, 

 and for that purpose it is necessary to inject greater quantities than 

 those w^hich may be indicated by any method of estimation. This rule 

 is applied as far as is possible at the Pasteur Institute. 



As regards vaccination against diphtheria of persons who are in 

 good health but are especially exposed to infection, the question 

 must be accepted as settled in the affirmative. 



From the commencement of our attempt to cure diphtheria by 

 means of a specific serum, the necessity was seen of protecting 

 children who were in contact with the sick persons against this 

 disease. Small quantities of serum were injected into such children 

 for protective purposes. The first results communicated in 1894 by 

 Roux to the Congress at Budapest being very encouraging, an attempt 

 was made to give the greatest possible extension to the system of 

 vaccination by antidiphtheria serum. In the following year, 1895, fairly 

 [522] numerous statistics had been collected, and Torday^ at Budapest, 

 1 Deutsche med. Wchnschr.^ Leipzig, 1895, S. 408. 



