224 10 



between the agglutinine and the combining-substance of the bacteria can be 

 expressed by the formula — 



C = KBVs 



where C = the quantity of combined agglutinine, /f = a constant, B = the quantity 

 of free agglutinine. 



Without entering more closely into the quantitative relations of the compounds 

 formed by the agglutinines and their nature, we may state that we have found 

 that the agglutinine combines with the B. coli "toxine" in quite different proportions. 



Omitting the details of these experiments, we may mention that the B. coli 



"toxine" employed was the bacterium-free filtrate of a B. coli bouillon-culture kept 



at 37° for 19 days. In the experiments we made, the amount of this "toxine" was 



kept constant, the quantity of immune-serum agglutinine exposed to its. powers of 



absorption being varied. It was found that with increasing amounts of agglutinine, 



its alisolute ul)sorption increased, while the coefficient of absorption — that is to say, 



the ratio of the quantity of agglutinine absorbed to the quantity originally present 



— remained practically unaltered within the limits of our experiments. The change 



in magnitude of the coefficient of absorption was, speaking generally, of such a 



nature that its value slowly diminished as the quantity of agglutinine exposed to 



its action grew less. This result is just the opposite of that found by Eisenberg & Volk 



C 

 in the case of the bacteria, so that the formula ^^r =" ^ calculated by Arkhenius 



BV: 



3 



on the basis of their figures does not hold good for the combining ratios of the 

 B. coli "toxine" and the agglutinine. To what extent these facts may modify the 

 present views of the laws that regulate the combinations of agglutinine with the 

 combining substance of the bacteria is being made the subject of further invest- 

 igation. 



C. The effect of heat on the bacterial emulsion. 



The diminished agglutinability of bacterial emulsions or suspensions that have 

 been heated has been noted by many experimenters. But the temperature at which 

 this change is first observed and the degree to which it proceeds have been very 

 differently recorded by the various authors, and they are far from unanimous in 

 their explanations of the phenomenon. 



Van de Vei.de, for example found that the agglutinability of his strain of B. 

 typhosus was not diminished when the suspension was heated to 60° for half an 

 hour, but that it fell to */75o of its original value when the suspension was heated 

 to 65° or 70° for a similar period. Nk:olle states that in many cases B. typhosus 



