Widal Reaction of Agglutination 507 



This occasional persistence of the reaction for years can lead to 

 errors of diagnosis, but is not apt to do so if the previous history of 

 the case can be properly studied. 



The agglutinating substance is present in the blood in the various 

 secretions extracted from it. Widal * says it has been found in the 

 blood, urine, the serous fluid from blisters, the pleural, pericardial, 

 and peritoneal fluids, milk, bile, seminal fluid, aqueous humor, tears, 

 pleural exudates, and to a less extent in the spleen, liver, and mesenteric 

 glands. Catrin f found it in the pus of a phlegmonous inflammation 

 occurring during typhoid fever, and Block in the typhoid stools. Thier- 

 celin { found it absent from the spontaneous sweat when present in 

 the blood and milk. 



The fact that the typhoid bacilli are scattered throughout the body 

 in small groups suggests that agglutination takes place in the circu- 

 lating blood of the infected individual. Salimbeni, however, asserts 

 that such agglutinations do not occur. 



The relation of the reaction to the germicidal activity of the blood 

 has been carefully studied, with the result of finding that the two 

 phenomena are different and depend upon different causes, though 

 occasionally present simultaneously in the same blood. It is only in 

 fresh blood that bacteriolysis is observed. Johnston and McTaggart 

 found that "with blood-solutions this phenomenon is frequently wit- 

 nessed. The clumped bacteria, if watched for an hour or so, may be 

 seen to break up into granules which gradually become indistinct 

 and vanish while under observation, until practically no trace remains 

 of the clumps which shortly before studded the entire field of the micro- 

 scope. The change is more liable to occur in cultures some days old 

 than in young cultures, and more likely with attenuated than with 

 virulent cultures." 



The agglutinative substance is different from the bactericidal sub- 

 stance, and the agglutination of the bacteria is not to be looked upon 

 as the beginning of their destruction. Agglutination takes place as 

 the result of contact with immune serum; bacteriolysis, only when 

 the bacteria, immune body, and proper complementary bodies are 

 all simultaneously present. Many typhoid serums with a high degree 

 of agglutinating power are entirely devoid of bactericidal powers. 



Jemmal || found that the phenomenon of agglutination was most 

 marked during the period of most intense infection and when the 

 bactericidal activity was greatest. Widal and Sicard ** also trace a 

 relationship between the two; but they were able to keep typhoid 

 cultures alive for two months in strongly agglutinative serums without 

 destroying their vitality ; and indeed, one of the original methods that 

 Widal suggested for studying the reaction required that the typhoid 

 bacillus should grow in diluted, but of course agglutinative, serum. 



Mosse and Dannie ft observed a case of typhoid during the eighth 

 month of pregnancy. At the time of delivery the blood and mammary 

 secretion of the mother and the blood of the child gave a positive 



* "Ann. de 1'Inst. Pasteur," May, 1897, No. 5. 



t "Gaz. de Med. de Paris," Oct. 15, 1896. 



J " Compte-rendu de la Soc. de Biol.," Dec. 19, 1896, No. 33. 



"Montreal Med. Jour.," March, 1897. 



|| "Centralbl. f. innere Med.," Jan. 23, 1897. 



** "Compte-rendu de la Soc. de Biol.," March, 1897, No. 8. 



tt Philadelphia Pediatric Society, 1897. 



