CULTURE MEDIA. 



57 



wardf* th(^y may bo ptontntHl for 15 to 2U minutos in the 

 storilizor on li successivo tlays. 



(/>) Lorrain Smith'B sorum. To each KK) cc. of 

 8orum add 1 to 1.5 cc of a 10 % solution of caustic soda. 

 Place in test tubos and troat as for Loctf'lor's sorum. 

 Or the tubes may be slanted, covered with tin foil and 

 placed in the steamer with the lid raised and exposed to 

 the steam for one hour. Afterwards they may be 

 steamed for 15 to 20 minutes on 3 successive days. 



(r) Kanthack and Stephen's serum agar mixture. 

 In making this culture material it is first nect^ssary to 

 determine the amount of 10% caustic soda (or potasli) 

 that will be needed to transform the albumins of the 

 serum into alkali albumins, so that no coagulation 

 occurs on boiling. 2 cc. is about the usual amount re- 

 quired per 100 cc. of serum. 



To 100 cc. of the serum (or serous exudate) add 2 cc. 

 of 10 % caustic soda and 1 .5 grammes of prepared agar- 

 agar fibre. Boil up together and add 4 cc. glycerine 

 and .5 gramme of grape sugar. Again boil and filter, 

 using the warming funnel. 



This culture material can be treated as agar. It 

 possesses all the advantages of both serum and agar, 

 except the clearness of the latter material. 



Peptone solution of Dunham. To 100 cc. of dis- 

 tilled water add 1 gramme Witlo's or Fairchild's pep- 

 tone and .5 gramme of common salt. Boil together for 

 15 minutes, neutralize if necessary with sodium carbon- 

 ate and again bring to a boil. Filter into flasks or 







