664 Gaseous Edema 



other anaerobic device. The deeper colonies are the largest. 

 Sometimes the growth only takes place within 10-12 mm. 

 of the surface; at others, within 3-4 cm. of it. After re- 

 peated cultivation the organisms seem to become accus- 

 tomed to the presence of oxygen, and will grow higher up 

 in the tube than when freshly isolated. 



Colonies. The colonies seen in the culture media are 

 grayish-white or brownish -white by transmitted light, and 

 sometimes exhibit a central dark dot. At the end of twenty- 

 four hours the larger colonies do not exceed 0.5-1.0 mm. 

 in diameter, though they may subsequently attain a diameter 

 of 2-3 mm. or more. Their first appearance is as little 

 spheres or ovals, more or less flattened, with irregular con- 

 tours, due to the presence of small projecting prongs, which 

 are quite distinct under a lens. The colonies may appear as 

 little irregular masses with projections. 



After several days or weeks, single, well-shaped colonies 

 may attain a large size and be surrounded by projections, 

 either in the form of little knobs or spikes or of fine branch- 

 ings hair-like or feathery. Their appearance has been 

 compared to thistle-balls or powder-puffs and to thorn-apples. 

 When the growth takes place in the puncture, the feathery 

 projections are continuous. Bubbles of gas make their ap- 

 pearance in plain agar as well as in sugar-agar, though, of 

 course, less plentifully. They first appear in the line of 

 growth ; afterward throughout the agar, often at a distance 

 from the actual growth. Any fluid collecting about the bub- 

 bles or at the surface of the agar-agar may be turbid from 

 the presence of bacilli. The gas-production is more abun- 

 dant at 37 C. than at the room temperature. 



The agar-agar is not liquefied by the growth of the bacillus, 

 but is often broken up into fragments and forced into the 

 upper part of the tube by the excessive gas-production. 



In its growth the bacillus produces considerable acid. 



Bouillon. In bouillon growth does not occur in tubes 

 exposed to the air, but when the tubes are placed in Buchner's 

 jars, or kept under anaerobic conditions, it occurs with abun- 

 dant gas-formation, especially in glucose-bouillon, with the 

 formation of a frothy layer on the surface. The growth is 

 rapid in development, the bouillon becoming clouded in two 

 to three hours. After a few days the bacilli sediment and 

 the bouillon again becomes clear. The reaction of the bouil- 

 lon becomes strongly acid. 



