PAUL H. De KRUIF 



397 



pH 3.0 and 2.8 and + at pH 2.6 to 2.2 of the glycocoll-HCl series. 

 It would appear that the glycocoll or the anion of the acid has the 

 property of broadening the acid agglutination optima of Microbes 

 D and G, or of shifting the optima toward a zone of higher Ch+. 



These results led to experiments which suggest an explanation for 

 the granular growth of Microbe G in plain broth. Washed suspen- 

 sions of this organism in distilled water, pH 6.0, do not sediment. 

 On the other hand, rapid sedimentation occurs in plain broth at pH 

 7.4 to 7.0. This leads to the conclusion that broth contains a con- 

 stituent which, per se, agglutinates the Type G organisms, or which 

 has the property, like glycocoll, of shifting their acid agglutination 

 optimum. 



pH45 



Fig. 1. 



Preliminary experiments were made in which the flocculating effect 

 of the various components of plain broth were tested against washed 

 distilled water suspensions of Microbe G. The constituents tested 

 were beef infusion, peptone, and Na2HP04. 



Beef Infusion. — 500 gm. of chopped beef were extracted in 1,000 cc. of tap 

 water, in the ice box for 16 hours. The mixture was then boiled for 30 minutes, 

 filtered, titrated to pH 7.4, refiJtered, and sterilized in the autoclave. 



Peptone Solution. — 10 gm. of Fairchild's peptone were dissolved in 1,000 cc. 

 of distilled water, boiled for 30 minutes, filtered, adjusted to pH 7.4, and sterilized 

 in the autoclave. 



NaiHPOi.—\0 gm. of this salt were dissolved in one liter of distilled water 

 adjusted to pH 7.4, and sterilized in the autoclave. 



