618 APPLICATION OF METHODS OF BACTERIOLOGY 



FIG. 103 



reason, to detect. (Fig. 103.) As they gradually increase 

 in size the contents of the spheres become cloudy and 

 marked by fine radiating stripes, easily 

 to be detected with the aid of a small 

 hand-lens. In deep stab-cultures in agar- 

 agar and in gelatin development occurs 

 only along the track of puncture, at a 

 distance below the surface. Growth is 

 frequently accompanied by the produc- 

 tion of gas-bubbles. 



It causes rapid liquefaction of blood 

 serum, with production of gas-bubbles, 

 and in two or three days the entire 

 medium may have become converted 

 into a yellowish semifluid mass. 



The most satisfactory results in the 

 study of the colonies are obtained by the 

 use of plates of nutrient agar-agar kept 

 in a chamber in which all oxygen has 

 been replaced by hydrogen. The colo- 

 nies appear as dull whitish points, irreg- 

 ular in outline, and when viewed with a 

 low-power lens are seen to be marked by 

 a net-work of branching and interlacing 

 lines that radiate in an irregular way 

 from the center toward the periphery. 



It grows well at the ordinary tempera- 

 ture of the room, but reaches its highest 

 development at the temperature of the 

 body. 



It stains readily with the ordinary aniline dyes. It does 

 not stain by Gram's method. 



Colonies of the ba- 

 cillus of malignant 

 edema in deep gela- 

 tin culture. ' (After 

 FrankelandPfeiffer.) 



