1074 SOCIÉTÉ DE BIOLOGIE 



which the Streptococci will appear in the médium from one to Iwo 

 hours, depending upon the time required to bring the culture up to the 

 optimum température for the growth of Streptococci. The rapid 

 growth of Streptoccoci in this médium during the fîrst 4 to 6 hours 

 makes it of value in the isolation of thèse organisms, as it may be usued 

 to ihcrease their numbers before seeding blood agar plates or other 

 suitable solid média. 



Another important advantage that Ihe liver peptone médium has over 

 the other sélective média for streptococci is the fact that it not only pré- 

 serves the anaerobes but makes possible their tentative diagnosis 

 within twenty-four hours. Badllus Welchii {B. perfrlngens), if présent 

 after the twelfth hour, increases enormously so thaï by the end of 

 twenly-four hours it enlirely outgrow severy other organism wich we 

 hâve thus far tested and its growth is accompanied by the formation 

 of considérable araounts of gas. The présence of gas bubbles after 12 to 

 16 hours incubation in this médium which shows on microscopic exa- 

 mination nonmotile, encapsulated Gram positive bacilli is almost inva- 

 riably due to the présence of the B. Welchii. Vibrion septique tends to 

 form filaments and characteristic cenlral spores of the citron and barrel 

 shaped types. Badllus œdeviatiens and ail other anaerobes that are 

 found in wounds, if given sufficicnt time will form characteristic spores, 

 which taken wilh tiieir gênerai morphology frequently furnish a due 

 as to llie anaerobic organisms présent in the given wound. The B. 

 spoi'ogenes Fhows subterminal spores wilh blackening and digestion 

 of the inlerlobular connective tissue of the liver, whereas the B. putri- 

 ficus shows drumslick terminal spores wilh blackening, the spores 

 being more prominent than those found in cultures of B. letani. 



Media prepared by the addition of liver to stérile dislilled water or 

 physiologie saline fait lo show any appréciable growth as for as the 

 Streptococci are concerned. Streplococd that hâve been in glucose- 

 gélatine for many weeks grow at first very feebly and then more vigo- 

 rously in the liver peptone médium when there is an entire failure 

 to get any growth at ail on blood agar or blood trypsin agar plates. 

 They occasionally form short chains in this médium after being kept in 

 this glucose-gélatine even when originally of the long chain variely 

 but the chains increase in sixe on subséquent culture in this liver 

 peptone médium. 



The curve of growth of Streptococci in liver peptone médium would 

 indicate a rapid initial increase in their number. For Ihe first 

 2 hours the organisms are difficult to find and no cloiid is observable, 

 but after the lapse of from 3 to 5 hours they become easily demonslrable 

 bolli micro and macroscopically and continue lo increase for 10 to 

 12 hours unlil there is a heavy cloud after which there is a tendency 

 for Ihem lo setlle to Ihe bollom of Ihe tube. We hâve some évidence 



