AGGLUTINATED TYPHOID BACILLI. 



149 



only " complete agglutination " and the " positively distinct agglu- 

 tination " are regarded as positive; everything at all doubtful is 

 regarded as not agglutinated. 



The first question was on which day following the injection the 

 maximum agglutinating value was to be expected in the serum of 

 the animals. Table II gives a resume of eight animals injected with 

 dead typhoid bacilli and examined at different times. 



TABLE II. 



Four of these animals exhibited a lower value on the 7th (or on 

 the 5th) day than on the 14th (or on the 10th) day. The other four 

 animals showed a decrease or no change at all in their agglutinating 

 values on the 5th, 9th, and 14th (or 5th and 10th) days. Hence 

 if on the 7th day we examined, as we actually did, the animals which 

 had been injected only with dead typhoid bacilli, we were not sure 

 that we should strike the maximum agglutinating value. That 

 we chose this time nevertheless is explained by the fact that this simpli- 

 fied the investigations, and by the further consideration that we 

 did not need the highest possible values in these control animals. 



The animals, however, in which we were compelled to strike the 

 maximum value are seen by reference to Table III to have behaved 

 differently. Of 15 animals which had been injected with dead, 

 agglutinated typhoid bacilli, there were only 3 which still showed 

 a slight increase of agglutinating value from the 7th to the 14th 

 (or 5th-9th) day. We were therefore justified in withdrawing the 



