A STUDY OF SPONTANEOUS AGGLUTINATION 



73 



broth. Tn many cases the broth was clear macroscopically, 

 but the clumps were visible when a hanging drop was examined. 

 I\Iore or less of the precipitate collected in the bottom of the 

 tubes. In some instances flocculi and a pellicle were visible on 

 the surface of the culture, and there was always a precipitation 

 in the bottom, either spontaneous or following agitation of 

 the tube. In other cases, small clumps could be seen with the 

 naked eye scattered throughout the culture. With the tjTihoid 

 and paratj'phoid bacilli there was a uniform cloudy growth and 

 apparently an absence of spontaneous agglutination when 



TABLE 1 



Varialionn of growth in broth medium. Cultures spontaneously agglutinated show 

 clear supernatant fluid, precipitation, pellicle, flocculi or small clumps, others 

 appear uniformly cloudy, to the naked eye like cultures not spontaneously 

 agglutinated 



A tabulation of our experiments shows the following results: Bact. pa-^a- 

 typhosum B showed precipitation with formation of pellicles and small clumps in 

 clear fluid in all cases with the exception of one strain. Bact. coli, 5 strains 

 exhibited this same phenomenon in every case. Bact. paratyphosum A showed 

 7 positive and 9 negative, Bact. typhosum 4 positive and 12 negative tests. 



examined with the naked eye, but with a hand lens, flocculi 

 were clearly visible in the supernatant fluid. 



We have, therefore, been led to conclude that in broth cul- 

 tures when flocculi are visible, macroscopic observation may be 

 relied upon; but in cloudy cultures, microscopic examination 

 should always be employed. 



In twenty-four hour cultures at 37°C., of microorganisms which 

 do not undergo spontaneous agglutination, the growth in pep- 

 ton water, glycerol or glucose broth, whether the reaction of the 

 media be acid, neutral or alkaline, is generally uniformly cloudy. 

 In some cases, however, there is a peUicle and SdccuU are seen 

 near the surface of such cultures. 



