94 BACTERIOLOGY 



placental blood. The preservation of blood-serum is sometimes 

 accomplished with chloroform, of which i per cent is to be added 

 to the medium; in this manner the serum may be preserved for a 

 long time. It may be filled into tubes, solidified and sterilized 

 as required; the chloroform will be driven off by the heat, owing 

 to its volatility. Blood-serum media which are sterilized at 

 low temperatures should be tested for twenty-four hours in the 

 incubator to prove that sterilization has been effective; if it has 

 not, development of the contaminating bacteria will take place 

 and be visible to the eye. 



Loffler's blood-serum consists of one part of bouillon con- 

 taining i per cent of glucose, mixed with three parts of blood- 

 serum. It is sterilized like ordinary blood-serum. It is used 

 largely for the cultivation of the bacillus of diphtheria. 



Fresh eggs in their shells may be used without other preparation 

 than washing the surface thoroughly with bichloride of mercury 

 solution; or after sterilization by steam, which of course coagu- 

 lates the albumen. The egg is easily inoculated through a small 

 opening made with a heated needle, which may be closed after- 

 ward with collodion. Hueppe recommended eggs closed in this 

 manner for the cultivation of anaerobic bacteria. 



Dorset's Egg Medium. 1 Perfectly fresh eggs are washed and 

 the shells sterilized with bichloride solution. The eggs are then 

 carefully broken and the yolks and whites mixed in a sterile 

 dish. The mixed material is poured into sterile tubes and solidi- 

 fied in the slanting position by heating at 70 75 C. for two 

 hours. Contamination with bacteria should be carefully avoided 

 throughout the preparation of the medium. The tubes should 

 be sealed with rubber caps or with wax and incubated for a 

 week before use. It is well to moisten the surface with a few 

 drops of sterile water from a pipette before inoculating the me- 

 dium. This medium is used for growing the tubercle bacillus. 



Bread-paste. Dry or toasted bread is broken into small 

 crumbs, filled into tubes or flasks, moistened with water and 



1 Dorset: American Medicine, April 5, 1902. 



