CULTURE MEDIA 61 



in these sterilised jars. Allow the jars to stand in a 

 cool place for twelve hours. Then pipette off the clear 

 serum with a sterile pipette, and fill the sterilised test- 

 tubes to the depth of 2-4 cm. The tubes are then 

 arranged in a sloping position on the shelves of the serum 

 inspissator, or failing this in a hot- water oven, the tem- 

 perature of which should be about 50 C. At this tempera- 

 ture they remain for thirty hours ; it is then raised to 

 65 C., at which temperature the serum coagulates in from 

 four to six hours and the tubes are now ready for use. It 

 is well, however, to place them in the blood-heat incu- 

 bator for a night, so that any contaminating bacteria may 

 form colonies, and the contaminated tubes may then be 

 rejected. 



Lqffler's blood-serum is prepared by adding one part 

 of glucose broth to three parts of the serum before inspissa- 

 tion. 



The serum inspissator is practically an incubator (see 

 p. 68) with slightly inclined (10-15) shelves, on which the 

 tubes rest, and thus the serum is coagulated in a sloping 

 position. 



Fluid serum, etc. Fluid blood-serum, ascitic and 

 hydrocele fluids, etc., are sometimes useful, and may be 

 used alone or mixed with peptone beef -broth in various 

 proportions. 



Ascitic or hydrocele fluid may be obtained by using 

 sterile trocars, etc., and carrying out the tapping with 

 aseptic precautions, collecting the fluid in sterilised flasks. 

 It is better to collect in several small flasks than in one 

 large one. 



Fluid blood- serum may be obtained by collecting blood 

 with aseptic precautions in sterilised flasks. When the 

 blood has coagulated and the serum separated, the serum 

 is pipetted off with a sterile pipette into sterile flasks. 



The flasks of serum, etc., should be kept in a warm 



