21 



ature between 35 and 37 C. The organism thus transferred 

 should multiply so that on the following day the liquid will 

 be cloudy. This is a bouillon culture of B. coli communis. 



19. Inoculating tubes of agar. Ordinarily the agar is 

 inclined before it is inoculated. In this case it is spoken of 

 as inclined or slant agar. Occasionally the agar is inocu- 

 lated without inclining it. Cultures made in this manner 

 are spoken of as "stab" or "stick" cultures, (i) In- 

 clined or slant agar. Stand a tube of agar in a wire basket 

 in a water bath and boil it until the agar is liquefied. (To 

 save repeating this it is well to incline the agar in several 

 tubes which can be kept for future use). Lay the tubes on 

 a tray, the top resting on the side of the tray so that the 

 surface of the agar will be about 4 cm. long, allow it to cool. 

 In placing the tubes the label should be up. When the 

 agar has set it is ready for use. It is inoculated precisely as 

 the bouillon excepting the loopful of culture is drawn over 

 the inclined surface instead of being thrust into the medium 

 as in the bouillon. Label and place it in the incubator with 

 the inoculated bouillon tube. On the following day there 

 should be a grayish growth on the surface of the agar covered 

 by the loop. This is an agar culture of B. coli communis. 

 (2) Stick cultures. These are made with a platinum needle 

 in the uninclined agar. The impregnated needle is pushed 

 down through the center of the agar. In all other respects 

 this culture is made like the slant agar culture. 



20. Inoculating the tube of gelatin. Tube cultures in 

 gelatin are usually made without inclining the gelatin, i.e. , 

 stick cultures. The tube of gelatin is inoculated in the 

 same manner as the stick culture in agar. This tube is to 

 be placed in the locker as the gelatin will melt at the incu- 

 bator temperature. The growth will appear in about two 

 days along the needle track. This is a gelatin culture of 

 B. coli communis. 



