490 PA THOGENIC BA CTERIA . 



blood-solutions this phenomenon is frequently witnessed. 

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

 be seen to break up in 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 microscope. The 

 change is more liable to occur in culture some days old 

 than in young cultures, and more likely with attenuated 

 than virulent cultures." It does not occur with all the 

 samples of typhoid blood, and is not well marked in very 

 dilute blood-solutions. 



The agglutinative substance is different from the bac- 

 tericidal substance, and the agglutination of the bacteria 

 is not to be looked upon as the beginning of their destruc- 

 tion. It was found by Widal and Sicard that many of 

 the typhoid serums with a high degree of agglutinating 

 power were entirely devoid of bactericidal powers. ' ' The 

 bactericidal, immunizing, and agglutinative properties 

 of the sera, although generally present at the same time, 

 are, however, mutually independent." 



Jemmal l found that the phenomenon of agglutination 

 was most marked during the period of most intense infec- 

 tion and when the bactericidal activity was greatest. 

 Widal and Sicard 2 also trace a relationship between 

 the two. 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. 



V. Transmission of the Agglutinating Power from 

 Parent to Child. — Mosse and Dannie 3 report the case of a 

 woman who had typhoid in the eighth month of pregnancy. 

 At the time of delivery the blood and mammary secretion 

 of the mother gave a positive reaction, and the blood of the 



1 Ceniralbl. f. inner e Med., Jan. 23, 1897. 



'. Compt. rendu de la Soc. de Biol., Mar., 1897, No. 8. 



s Philadelphia Pediatric Society, 1897. 



