TYPHOID FEVER. 493 



agglutinative power, whereby degrees of this power may 

 be obtained which are entirely unknown during natural 

 infection. There is, however, no necessary correspond- 

 ence between the height of immunity and that of aggluti- 

 nation; especially may the latter lessen or disappear when 

 the former is present. 



On the other hand, the power of agglutination often 

 occurs almost simultaneously with the onset of the disease, 

 when no immunity can have been established; many cases 

 with a high degree of agglutinating power are without 

 immunity and suffer relapses; and the phenomenon is 

 most marked during the acme of the disease, and it sub- 

 sequently declines. The facts that the phenomenon is 

 more marked in bad cases than in mild ones, and that 

 the blood possesses a higher degree of agglutinating 

 power after relapses, are given little weight in the argu- 

 ment, for, supposing the most recent view of Widal to be 

 correct, and the reaction to be simply a phenomenon of 

 infection, it is only to be expected that the results of 

 severe infection should be greater than those of mild 

 infection, and of prolonged infection than of brief ill- 

 nesses. 



Relapses have also occurred in cases in which the blood 

 showed an agglutinating strength operative in dilution 

 of i : 2000. 



Unable to prove that a definite relationship between 

 immunity and the agglutinative power of the blood 

 exists, most thinkers have now adopted Widal's view, 

 and look upon the reaction simply as a u phenomenon of 

 infection." 



Malvoz 1 looks upon the phenomenon as depending upon 

 metabolic products of the bacteria which are accumulated 

 in the body during the disease. His proof is found in the 

 effect of certain chemic substances which agglutinate, 

 and in the effects of old upon fresh cultures. 



He says: "If we take an emulsion of the first vaccine of 

 anthrax, made by thoroughly mixing some of the culture with 

 1 Ann. de T Inst. Pasteur, August 25, 1889. 



