QUALITATIVE BACTERIOLOGICAL ANALYSIS. 177 



Eberthiform bacilli when injected into animals, before the 

 transformation had taken place, were found capable of producing a 

 serum which in high dilutions readily agglutinated typical 

 typhoid bacilli. Sacquepee believes that Eberthiform bacilli 

 found in water have been derived from typhoid stools, the 

 transformation from the true typhoid bacillus to the Eber- 

 thiform variety having taken place within the human body. 

 He could not convert B. coli into the Eberthiform variety, 

 but found that true typhoid bacilli introduced into collodion 

 bags and then placed in the peritoneal cavity of a white rat, 

 which had been strongly immunised by injections of B. typhosus, 

 were converted into the Eberthiform variety. The typhoid 

 bacilli so treated lost their susceptibility to specific agglutinins, 

 and produced a coloured growth on potato. SacquepeVs results 

 are very interesting, but require confirmation by other bacterio- 

 logists. In the present state of our knowledge I think a dilution 

 of 1-500 of anti-typhoid serum may be accepted as a fairly safe 

 working guide for the diagnosis of the true B. typhosus. 



(2) The Strength of the Specific Serum. Having considered 

 the first variable quantity of the agglutination test, viz., the 

 bacillus operated upon, it is necessary to mention a few points 

 in relation to the strength of the specific serum, because its 

 potency is intimately related to the dilution of the anti-typhoid 

 serum, which is to be employed in the routine test. It is well 

 known that sera prepared by immunising animals with cultures of 

 B. typhosus vary greatly in their power of causing agglutination 

 of this bacillus. At one time it was supposed that the 

 results were largely dependent on the virulence of the culture 

 used for the process of immunisation. Later experiments have 

 thrown some doubt on this theory, so the question must still be 

 considered sub judice. Whatever the explanation may be, the 

 fact remains that sera as prepared vary extremely in their 

 agglutinating action. The action of an anti-typhoid serum 

 appears to be more marked on the variety of the bacillus, by 

 means of which it has been prepared, than upon other varieties 

 of the organism ; that is to say, a serum has a " special " 

 action upon its own organism, and a non-special action varying 

 in degree on other varieties of the organism. Recognising 

 these facts, attempts have been made to prepare polyvalent 



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