INOCULATING TUBES OF BOUILLON 15 



plugs replaced in their respective tubes, and the loop flamed 

 and put aside. Label the freshly inoculated tube with the 

 name of the organism, source, and date. Stand it in a tray or 

 cup and place it in the incubator. 1 This should be kept at a 

 temperature between 35 and 37 C. The organism thus trans- 

 ferred should multiply so that on the following day the liquid 

 will be cloudy. It is then a bouillon culture of B. coli corn- 

 mums. 



21. Inoculating tubes of agar. Ordinarily the cigar is 

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

 inclined or slant agar. Occasionally the agar is inoculated 

 without inclining it. Cultures made in this manner are spoken 

 of as "stab" or "stick" cultures, (a) Inclined 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, but after the slants have been made for a long 

 time it is better to boil and reslant them, especially if they 

 are to be used for organisms which do not grow well on a dry 

 surface.) Lay the tube on a tray, the top resting on the side 

 of the tray so that the surface of the agar w r ill be about 4 cm. 

 long, and 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 that the loop- 

 ful 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-white growth 



1 For illustrations and descriptions of different kinds of incubators, 

 see text-books. It is desirable to note especially the various burners and 

 thermoregulators employed to heat and regulate the temperature of 

 the incubators. Considerable information may also be acquired by 

 carefully looking through the catalogues of manufacturers and dealers 

 in bacteriologic apparatus. Copies of some of these will be found on 

 the reference bookshelves. 



