126 LABORATORY GUIDE IN BACTERIOLOGY 



13. Boil 2 minutes over free flame, constantly stirring. 



14. Make up loss by evaporation. . t. /-, 



15. Filter through absorbent cotton and cotton flannel, passmg the filtrate 



through the filter until clear. 



16. Titrate and record final reaction. 



17. Tube, using 10 c.c. in each tube in the case of gelatin and agar. 



18. Sterilize 5 minutes in the autoclav at 120°, or for 30 minutes in streaming 



steam on 3 successive days. Put at once into ice-water till solidified. 



19. Store in the ice-chest in a moist atmosphere to prevent evaporation. 



Blood-serum — 



I. Fresh ox blood collected in sterile jars (museum jars) 



Fig. 37 

 Koch Inspissator 



The 



is set in the ice-chest until the serum has separated, 

 serum is filtered if necessary. 



2. Take 3 parts of this freshly prepared serum and i part 

 of broth containing 1.5 per cent, glucose, and mix. 



