3 8o 



Gaseous Edema 





r 



Cultivation. Gelatin. It grows in ordinary neutral or 

 alkaline gelatin, but better in gelatin 

 containing glucose, in which the char- 

 acteristic gas production is marked. 

 Soft media, made with 5 instead ot 

 10 per cent, of the crude gelatin, is 

 said to be better than the standard 

 preparation. 



There is no distinct liquefaction of 

 the medium, but in 5 per cent, gelatin 

 softening can sometimes be demon- 

 strated by tilting the tube and observ- 

 ing that the gas bubbles change their 

 position, as well as by noticing that 

 the growth tends to sediment. 



Agar-agar. In making agar-agar 

 cultures careful anaerobic precautions 

 must be observed. The tubes should 

 contain considerably more than the 

 usual quantity of the medium, which 

 should be boiled and freshly solidified 

 before using. The implantation should 

 be deeply made with a long wire. The 

 growth takes place slowly unless such 

 tubes are placed in a Buchner's jar or 

 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 repeated 

 cultivation the organisms seem to 

 become accustomed 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- 

 i.o mm. in diameter, though they 

 may subsequently attain a diameter 

 of 23 mm. or more. Their first appearance is as little 



Fig. 1 1 6. Bacillus 

 aerogenes capsulatus, 

 with gas production 

 (from photograph by 

 Prof. Simon Flexner). 



