140 



MEDICAL BACTERIOLOGY 



vessel leaving the clear serum on the top and at the sides. This 

 can now be pipetted or siphoned off. If the serum contains a large 

 number of red blood corpuscles it can be placed in rather tall cylin- 

 ders (graduates) and allowed to stand 24 hours longer, when the 

 clear straw colored serum can be readily separated. This may be 

 preserved for a long time by the addition of %% chloroform and 

 kept in a tightly corked bottle in a cool place. 



c. Loeffler's mixture. This consists of 3 parts of blood serum 

 and 1 part of \% dextrose bouillon. 



d. Sterilization. Fill sterile test-tubes (about 3 cm. deep) with 

 the serum mixture and place them im- 



mediately in a sloping position in an 

 inspissator (Fig. 31), or steamer and 

 heat to 95 C. for 1 hour on three con- 

 secutive days. If a higher tempera- 

 ture be employed bubbles are formed 

 which rupture the surface of the me- 

 dium in their escape. When steril- 

 ized the tubes should be sealed with 

 paraffin or otherwise. 



REFERENCES. A. 110; H. 51; M. 



&T? AQ i\/rTn 1 on XT 

 K. 4o ; Me.b . Io7 ; JN. 



T> 

 r. 



PIG. 31. Blood Serum Inspissator, 

 (Muir & Ritchie). 



