CULTURE-MEDIA. 69 



ococcus. One part of placental blood-serum, or pleuritic 

 serum, or hydrocele fluid, is mixed with one to two parts of 

 nutrient agar in the fluid condition. It must be divided into 

 tubes before solidification. Solidify in a slanting position; 

 subsequently sterilize at 75° C. so as not to coagulate the albu- 

 men of the blood-serum. The nutrient agar in this case should 

 contain 2 per cent, of dry agar. 



Another expedient has also been to smear a httle blood, drawn from a 

 puncture made by a sterile needle in the carefully cleaned finger, over 

 the surface of a tube of nutrient agar — hlood-agar — used for cultivating the 

 bacillus of influenza. Small quantities of blood may be drawn from a vein 

 in the ear of a rabbit (see page 94) with a sterile hypodermic syringe, and 

 is quickly divided among three or four tubes of agar, melted in the upper 

 third; slant the tubes while cooling. To make a large amount of blood-agar, 

 bleed a rabbit from the carotid artery into a sterile flask containing pieces 

 of sterile glass tubing; shake the flask constantly; divide the defibrinated 

 blood among tubes containing sterile nutrient agar; slant the tubes while 

 cooling. Use about one part of blood to about three of agar. Great care 

 must be used not to contaminate the blood as it is drawn. The tubes when 

 completed should stand some days before using, so that contaminating bacteria 

 if present may grow in the interval and permit such tubes to be discarded. 

 Guarnieri's medium consists of a mixture of gelatin and agar. 

 Eggs in their shells may be used after sterilization by steam, which of course 

 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 technique. 

 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 



* American Medicine. April 5, 1902. 



