LOFFLER'S BLOOD SERUM MIXTURE 119 



BLOOD AGAR 



Is prepared by adding to melted agar sterile defibrinated blood 

 of any animal in the proportion of i of blood to 5 of agar. The 

 mixture may then be allowed to harden in a slanting position or 

 poured into plates. 



BLOOD SERUM 



The blood of a dog, sheep or cow drawn under strictly aseptic 

 precautions is collected in a sterile jar and after the serum has 

 separated, it is run into tubes by sterile pipettes and simply 

 coagulated by heat. Sterilization is not necessary, and is harm- 

 ful for the growth of the tubercle bacilli, because salts are formed 

 which interfere with the growth of the bacteria. If this serum 

 be mixed with 3 or 4 parts of distilled water and sterilized five 

 days in the Arnold at 7oC. it will be a slightly turbid, opalescent 

 liquid very suitable for many organisms, particularly cocci. 

 This medium with the addition of bits of animal tissue is a good 

 medium for spirochaetes. 



LOFFLER'S BLOOD SERUM MIXTURE 



Blood serum of an ox, a sheep or a horse is employed, mixed 

 with bouillon containing i percent of grape sugar. 



Seventy-five percent of blood serum is mixed with 25 percent 

 bouillon. This is run into sterilized tubes and the latter are 

 placed in a blood serum coagulator and coagulated in a sloping 

 position at a temperature of 65C. or thereabouts. 



After they are coagulated they are sterilized by heating an 

 hour each day at 65C. five successive days, or at 95C. for an 

 hour on three successive days. After sterilization the tubes 

 should be sealed carefully. 



Ascitic and hydrocele fluids may be used for this medium or 

 in the liquid form combined with plain broth; they need no 

 addition of sugar as they contain a small percentage. 



