SÉANCE DU 16 NOVEMBKE 1073 



mentation not only with various kinds of méat but with média having 

 various reactions. It has been possible to formulate Ihese factors so 

 that we are able to présent for considération a médium wliich is simple 

 in its préparation, which is peculiarly favorable to the growth of Strep- 

 tococci and which will, because of its protein content and anaerobic 

 nature, conserve anaerobic Bacilli and Streptococci présent in wounds. 



This médium consists of peptone water which has been alkalinized to 

 a minus 2 reaction to phenolphtalein to which a small amount of beef, 

 rabbitor human liver has been added. The liver peptone water is pre- 

 pared as foUows : add peptone, 10 grammes and sodium chloride, 

 5 grammes to (distilled) water 1.000 ccm. Dissolve by boiling 30 mi- 

 nutes ; neutralize to phenolphtalein, then add 20 ccm. of normal sodium 

 hydrate solution; autoclave for 15 minutes at 115 degrees G. : filter; 

 tube (placing 10.0 ccm. in each tube) and add approximately 1 gramme 

 of Rabbit, beef or human liver. Autoclave for 15 minutes at 115 degrees 

 C; incubate for three days to insure sterilily (if stérile, fluid will 

 remain clear — it may assume a faint yellow color). In the préparation 

 of the médium two things are of especial importance : 1 — the reaction 

 and 2 — the amount of liver. The reaction is made a minus 2 which 

 suffîces to neutralize the acids contained within the liver cube. It has 

 been found désirable to hâve the final reaction neutral or slightly alka- 

 line. In expérimental work it has been discovered that Streptococcj 

 grew very well in a fairly alkalinized médium of this type but that 

 growth rapidly ceases as the acidity is increased. The point of best 

 growth has a moderato range on both sides of the neutral point but 

 safety lies on the alkaline side as the range of certainty of growth is 

 greater in alkaline média than it is when the médium tends to become 

 even slightly acidin reaction. This point bears emphasis for itis obvious 

 that in placing a variable amount of liver tissue of an uknown acid reac- 

 tion it is important that in the final reaction the neutral point shall not 

 be passed on the side of acidity. It is for this reason that fresh liver 

 tissue is preferred though it is true that equally good resulls hâve been 

 obtainedwith the liver bought in the market or obtained at the autopsy 

 table. The standard amount of liver used in a tube is a cube of one 

 cm. dimensions which will weigh about one gramme ; and which is 

 roughly blocked out by the eye, there being found in fact only slight 

 variations after a little practice in making the mediuni. 



Of ail the various média that we hâve used for growing Streptococci 

 this liver peptone médium has given the best results in respect to rapi- 

 dity of growth — often 3 to 4 hours after inoculation chains are easily 

 found in the hanging drop and if the inoculation contains streptococci 

 at ail they can invariably be found in 6 to 7 hours. For rapidity of dia- 

 gnosis it is essential that the médium be at incubator température at the 

 time the inoculation is made. Cold tubes will increase the time in 



