1 68 CULTURE MEDIA 



soda solution required to make the reaction of the 

 medium mass + 10 (i. e., calculated for 1000 c.c., less 

 the quantity used for the titrations). 



8. Add the necessary amount of soda solution and 

 replace in the steamer for twenty minutes (to complete 

 the precipitation of the phosphates, etc.) . 



9. Allow the medium mass to cool to 60 C. Well 

 whip the whites of two eggs, add to the contents of 

 the flask, and replace in the steamer at 100 C. for 

 about one hour (until the egg-albumen has coagulated 

 and formed large, firm masses floating on and in clear 

 agar.) 



10. Filter through papier Char din, by the aid of a 

 hot-water funnel, if necessary (Fig. 101), into a sterile 

 flask. 



11. Tube in quantities of 10 c.c. or 15 c.c. 



12. Sterilise in the steamer at 100 C. for thirty 

 minutes on each of three consecutive days i. e., by the 

 discontinuous method. 



Blood=serum (Inspissated). 



1. Sterilise cylindrical glass jar (Fig. 109) and its 

 cover by dry heat, or by washing first with ether and 

 then with alcohol and drying. 



2 . Collect blood at the slaughter house from ox or 

 sheep in the sterile cylinder. 



3. Allow the vessel to stand for fifteen minutes for 

 the blood to coagulate. (This must be done before 

 leaving the slaughter-house, otherwise the serum will 

 be stained with haemoglobin.) 



4. Separate the clot from the sides of the vessel by 

 means of a sterile glass rod (the yield of serum is much 

 smaller when this is not done), and place the cylinder 

 in the ice-chest for twenty-four hours. 



5. Remove the serum with sterile pipettes, or syphon 

 it off, and fill into sterile tubes (5 c.c. in each) or 

 flasks. 



