The study of the great group of microbes, for which 

 Bacillus lyphosus and Bacterium coli are the two 

 predominant types, is getting more and more im- 

 portant.This is of course for a good deal due to their 

 great practical signification, but also a considerable the- 

 oretical interest is involved in the solution of the pro- 

 blems connected with them. A great deal of work has 

 been done to penetrate into the characteristics of these or- 

 ganisms and to make a thorough study of every one of 

 their peculiar features. Amongst these their faculty to 

 produce agglutinins has during the last years attracted 

 the greatest attention and has been studied from several 

 points of view. 



About the fluctuations in agglutinating power, which 

 are going on into an animal, actively immunised against 

 the said microbes, some information could be found 

 scattered into the papers of a few investigators (Deutsch, 

 Durham, Neisser); but a greater number of experiments 

 in this line were first carried out by Jergensen and 

 Madsen. In the case of goats and rabbits, which were 

 immunised against B. typhos. and Vb. cholerae it was 

 found, that after an injection of these microorganisms 

 fluctuations in the agglutinating faculty of the blood oc- 

 curred, which were very like those previously observed 

 during active immunisation against the toxins of tetanus 



