404 CLINICAL BACTERIOLOGY. 



gen, but then without the development of red pigment. It is 

 somewhat pathogenic, inoculated animals dying with toxic 

 symptoms after introduction of large amounts. The name pro- 

 digiosus is derived from the fact that the bloody appearance of 

 the so-called miraculous holy wafers is attributed to infection 

 with this microorganism. 



17. Among other pigment-producing bacteria characterized 

 only by the color of their cultures may be mentioned the 

 bacillus ruber balticus, bacillus ruber aquatilis, bacillus cceruleus, 

 bacillus pavonmus, bacillus amethystinus. 



(b) Nonchromogenic. 



18. Bacillus Liquefaciens . This is one of the most wide- 

 spread of the water-bacilli. It is an actively motile rod, often 

 joined in short chains of four or more segments. It rapidly 

 liquefies gelatin. In plates it assumes the form of a dish, upon 

 the base of which lies a gray, bacterial mass. In stab-cultures 

 the growth assumes the form of a stocking, with a dilated upper 

 portion. The odor of the culture is highly disagreeable. The 

 bacillus exhibits facultative anaerobiosis. In nutrient media 

 containing nitrates it generates nitrous acid. 



The following likewise are included among water-bacteria : 

 ip. Bacillus Liquidis. This is a short, plump, slightly motile 

 bacillus, which also rapidly liquefies gelatin. In tubes the 

 gray, liquefied gelatin becomes covered with a thin membrane, 

 which sinks to the bottom on agitation. 



20. Bacillus A quatilis. This is a slender rod, with spontane- 

 ous motility. It liquefies gelatin slowly, and according to some 

 observers not at all. It grows in gelatin upon the surface in the 

 form of small, yellowish colonies, and upon potatoes with a 

 scanty yellow deposit. 



In the earth and in certain articles of food the following 

 bacteria are always to be found, which are characterized by 

 especial resistance of their spores : 



21. Root-bacillus. This is a large, thick bacillus, with rounded 

 extremities, and possessing slight motility. It develops central 

 spores, and growth takes place only in the presence of oxygen. 

 The whitish-gray colonies that form consist of a network of fine, 

 interlacing threads. They liquefy gelatin. In stab-cultures 

 also filaments and processes form, and an appearance results re- 

 sembling an inverted fir-tree. Upon agar-agar a network forms 

 suggesting the ramifications of the roots of a tree. 



22. Bacillus Subtilis {Hay-bacillus}. This is a large, deli- 

 cate bacillus that often develops into long, straight threads. 

 The bacillus subtilis is a strictly aerobic organism, and it quickly 

 liquefies gelatin. The temperature-optimum is 30 C. (86 F.); 

 the temperature-minimum, 10 C. (50 F.); the temperature- 

 maximum, 45 C. (113 F.). Upon plates the bright, grayish- 



