24 CULTURE MEDIA. 



room and the next morning the more or less clear serum will have been 

 squeezed out from the clot. Collect this serum and keep in the ice 

 chest for future use. If to be kept for a long time, it is advisable to add 

 about 2% of chloroform to the serum. This will not only keep the 

 serum, but will eventually sterilize it. 



To make Loffler's serum, take one part of glucose bouillon and 

 three parts of blood-serum. Mix, tube and coagulate the albumin in 

 the inspissator or rice cooker, giving the tubes a proper slant before 

 heating. Sterilize the following day in the autoclave as previously 

 directed or in the Arnold on three successive days. 



A SUBSTITUTE FOR ORDINARY BLOOD -SERUM. 



Purchase a good article of commercial blood-serum albumin and 

 make a 15% solution of it in glucose bouillon. Tube and inspissate as 

 for blood-serum. If made with glycerin bouillon, it makes a good 

 medium for tubercle bacilli. 



As this dried blood albumin only costs about fifty cents a pound 

 and will keep permanently, it is exceedingly convenient for those not 

 near an abattoir. Its use was first suggested by Hospital Steward King, 

 of this laboratory, and I cannot find that it has been previously used 

 as a substitute for fresh blood-serum. 



At any rate, the results with it as a culture medium seem to be the 

 same as with the fresh serum. 



This is better than the various white of egg substitutes usually 

 recommended. 



HYDROCELE, AND BLOOD AGAR. 



To tubes of melted agar at 50 C. add from one to three c.c. of 

 hydrocele or ascitic fluid, observing aseptic precautions. For blood 

 agar the blood from a vein should be received into a sodium citrate salt 

 solution to prevent coagulation, and added subsequently as for hydro- 

 cele fluid. Allow the agar to solidify as a slant. 



BLOOD-STREAKED AGAR. 



Sterilize the lobe of the ear and puncture with a sterile needle. 

 Collect the exuding blood on a large platinum loop and smear it over 



