76 MANUAL OF BACTERIOLOGY. 



coagulates the albumen. The egg is easily inoculated through a small opening 

 made with a heated needle, which may be closed afterward with collodion. 

 Egg-albumen has been used as a constituent of various media. Dorset* has 

 found that eggs furnish an excellent culture-medium for tubercle bacilli. The 

 yolk and the white are mixed, poured into tubes, slanted, coagulated, and 

 sterilized. Just before using pour into the tube a few drops of sterile distilled 

 water to moisten the medium. This is a most valuable addition to the technic. 

 Bread-paste (finely-divided dry bread, mixed with water and sterilized) is 

 used for the cultivation of moulds. Sabouraud recommends the following for 

 the cultivation of the trichophyton fungus : 



Peptone . . 5.0 grams. 



Maltose . . 3.8 grams. 



Agar .... .1.3 grams. 



Water . . ... . . loo.o c.c. 



Test-tubes. — Bacteria are generally cultivated in test-tubes. 

 A convenient size is one f of an inch in diameter and 5 inches 

 in length. The tubes should be of a heavier glass than in those 

 used for ordinary chemical work. The New York Board of 

 Health, and some others, use a tube three inches in length with- 

 out a flange for the cultivation of the diphtheria bacillus on 

 Loffler's blood-serum mixture. Test-tubes should be thor- 

 oughly cleaned with a swab before using; they should be boiled 

 with washing-soda, rinsed, filled with hydrochloric acid solu- 

 tion, rinsed and inverted to drain away the fluid. 



Plugs of raw cotton or cotton batting are employed as stop- 

 pers. Some prefer absorbent cotton, but it is likely to become 

 soggy after exposure to steam. The plug should fit smoothly; 

 creases and cracks around the edges are to be avoided. The 

 plug should be tight enough to sustain the weight of the tube 

 when held by the plug. These plugs prevent bacteria from 

 entering or leaving the tubes. 



Sterilization of Test-tubes.— The tubes are to be sterilized 

 in a hot-air sterilizer for one hour, at a temperature of 150° 

 C. They may be left in until the cotton acquires a light-brown 

 color, but it should not be burned. If the plugs touch the sides 

 of the sterilizer or lie against the bottom they may be scorched. 

 *American Medicine. April 5, r902. 



