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information to be used in the daily routine work of a practical 

 laboratory. It is probable however that the agglutination-test 

 may prove to be of great value for the diphtheria diagnosis. 



Much longer I should like to dwell on what was mentioned in 

 the third place, namely the estimation of the virulence. For this 

 purpose guinea-pigs are generally employed. A certain quantity 

 of a toxin-containing medium is injected subcutaneously or a 

 small portion of the culture is inoculated cutaneously. In the 

 first case we try to give such a quantity of toxin that the 

 animal is killed within a few days and on obduction the 

 charteracistic symptoms of diphtheria-death are looked for, namely 

 subcutaneous oedema at the seat of the inoculation, a serous 

 exsudate in the pleural cavity and pericardium and enlargement 

 with strong hyperaemia of the suprarenal glands. By the cutané 

 inoculation we intend to get a local reaction, which presents itself 

 at first as an infiltration, afterwards as a necrosis of the skin. 



As I noticed before the simultaneous inoculation of a control 

 guinea-pig, having recieved a dose of antitoxin, may greatly 

 increase the importance of a positive result. 



Let me now give an outline of the course which is followed 

 by the method of such a virulence-estimation. Of a small portion 

 of the mucous membrane of throat or nose a little of the 

 secretion-product is taken, this is rubbed over the surface of 

 a culture-medium, hoping that every bacterium present will 

 form a separate colony and if necessary, culturing is repeated 

 on a new medium till we reach our end. Thus we go out 

 for our further investigations if possible from one or otherwise 

 from a few bacilli. Of the descendents of this bacillus we want 

 to make sure whether any toxin is formed or not. 



It is kwown however, that the toxinproduction is dependent 

 on various circumstances, e. g. the composition of the medium, 

 the length of growth, the temperature etc. By the estimation 

 of the pathogenicity, as far as the practical side is concerned, 

 no attention can be paid to these matters without making the 

 experiment too extensive. In all cases one fixed scheme has to 

 be followed. This takes place either by inoculation directly 

 from a serum-culture as soon as a pure culture is obtained, 

 or by inoculating after the bacteria have grown for a certain 

 time, fixed for all cases, in some liquid medium. Now we al- 



