208 SPECIAL MEDIA 



4. Render the reaction of the medium neutral to litmus 

 paper by the cautious addition of normal caustic soda. 



5. Tube in quantities of 10 c.c. and sterilise in the steamer at 

 100 C. for twenty minutes on each of three successive days. 



6. Store for use in a cool dark place. 



B. Diphtheria. 



Glycerine Blood=serum. 



1. Prepare blood-serum as described, page 168, sections i to 4. 



2. Add 5 per cent, pure glycerine. 



3. Complete as described above for ordinary blood-serum, 

 sections 5 to 7. 



NOTE. Different percentages of glycerine from 4 per cent, 

 to 8 per cent. are used for special purposes. Five per cent, is 

 that usually employed. 



Blood =serum (Loeffler). 



1. Prepare nutrient bouillon (vide page 163), using meat 

 extract made from veal instead of beef. 



2. Add i per cent, glucose to the bouillon, and allow it to 

 dissolve completely. 



3. Now add 300 c.c. clear blood-serum (vide page 168, sections 

 i to 4) to every 100 c.c. of this bouillon. 



4. Fill into sterile tubes and complete as for ordinary blood- 

 serum. 



Blood=serum (Lorrain Smith). 



1. Collect blood-serum (vide page 168, sections i to 4), as free 

 from haemoglobin as possible. 



2. Weigh out 0.15 per cent, sodium hydrate and dissolve it 

 in the fluid (or add 0.375 c - c> f dekanormal soda solution for 

 every 100 c.c. of serum). 



3. Tube, and stiffen at 100 C. in the serum inspissator. 



4. Incubate at 37 C. for forty-eight hours to eliminate any 

 contaminated tubes. Store the remainder for future use. 



Blood Serum (Councilman and Mallory). 



1. Collect blood serum in slaughterhouse, coagulate, remove 

 serum and tube (vide page 168). 



Great care must be taken to avoid the inclusion of air bubbles 

 indeed if only a few tubes are filled at one time, it is a good plan 

 to stand them upright in the receiver of an air pump and to ex- 

 haust as completely as possible before transferring to the serum 

 inspissator. 



2. Heat the tubes in a slanting position in hot-air steriliser at 

 90 C. till firmly coagulated, say half an hour. 



