218 BACTERIA PATHOGENIC TO MAN 



twenty-four hours on the ice, and then the serum which surrounds the 

 clot is syphoned off by a rubber tube and mixed with one-third its quan- 

 tity of nutrient beef-broth, to which 1 per cent, glucose has been added. 

 This constitutes the Loeffler blood-serum mixture. This is poured 

 into tubes, which should be about four inches in length and one-half 

 of an inch in diameter, having been previously plugged with cotton 

 and sterilized by dry heat at 150 C. for one hour. Care should be 

 taken in filling the tubes to avoid the formation of air bubbles, as they 

 leave a permanently uneven surface when the serum has been coagu- 

 lated by heat. To prevent this the end of the pipette or funnel which 

 contains the serum should be inserted well into the test-tube. About 

 3 c.c. are sufficient for each tube if the small size is employed, if 

 not 5 c.c. are required. The tubes, having been filled to the 

 required height, are now to be coagulated and sterilized. They 

 are placed slanted at the proper angle and then kept for two hours 

 at a temperature just below 95 C. For this purpose a Koch serum 

 coagulator or a double boiler serves best, though a steam sterilizer 

 will suffice. If the latter is used a wire frame must be arranged to hold 

 the tubes at the proper inclination, and the degree of heat must be 

 carefully watched, as otherwise the temperature may go too high, and 

 if the serum is actually boiled the culture medium will be spoiled. After 

 sterilization by this process the tubes containing the sterile, solidified 

 blood serum can be placed in covered tin boxes, or stopped with sterile 

 paraffined corks and kept for months. The serum thus prepared is 

 quite opaque and firm. 



Swab for Inoculating Culture Tubes. The swab we use to inocu- 

 late the serum is made as follows : A stiff, thin, iron rod, six inches in 

 length, is roughened at one end by a few blows of a hammer, and about 

 this end a little absorbent cotton is firmly wound. Each swab is then 

 placed in a separate glass tube, and the mouths of the tubes are plugged 

 with cotton. The tubes and rods are then sterilized by dry heat at 

 about 150 C. for one hour, and stored for future use. These cotton 

 swabs have proved much more serviceable for making inoculations 

 than platinum-wire needles or wooden sticks, especially in young chil- 

 dren and in laryngeal cases. It is easier to use the cotton swab in such 

 cases, and it gathers up so much more material for the inoculation 

 that it has seemed more reliable. 



For convenience and safety in transportation "culture outfits" have 

 been devised, which consist usually of a small wooden box containing 

 a tube of blood serum, a tube holding a swab, and a record blank. 

 These "culture outfits" may be carried or sent by messenger or express 

 to any place desired. 



Directions for Inoculating Culture Tubes with the Exudate. The 

 patient is placed in a good light, and, if a child, properly held. The 

 swab is removed from its tube, and, while the tongue is depressed with 

 a spoon, is passed into the pharynx (if possible, without touching the 

 tongue or other parts of the mouth) and is rubbed gently but firmly 

 against any visible membrane on the tonsils or in the pharynx, and 



