114 BACTERIOLOGY 



of flagella, and a disposition to unite into groups. Owing to 

 their motility, the bacilli, or the threads formed by them, 

 are seen to dart with an undulating motion across the field 

 of the microscope. On the gelatine plate little white dots 

 occur, which soon extend and liquefy the gelatine over a 

 still wider surrounding area, while around the liquefied 

 mass fibres of bacilli are moreover seen growing into the 

 gelatine in the form of a halo. Thrust-cultures likewise 

 show an energetic liquefaction (fig. 39), and as soon as the 

 gelatine in the test-tube has become completely fluid a coat- 

 ing or pellicle forms on the surface. An extensive growth 

 develops upon agar, and on potato there appears a creamy 

 deposit, which in a few days takes the colour of wine. 

 Serum and the coagulated albumen from plovers' and 

 pigeons' eggs are liquefied, and on these also the superficial 

 formation of membrane is very marked. According to 

 Wyssokowitsch, if the spores are introduced into the circu- 

 lation they expand into,, rods, and remain lying in the liver 

 and spleen without exercising any influence on the organ- 

 ism. According to Vandervelde, the Bacillus subtilis sett 

 up active fermentation of sugar. 



Bacillus prodigiosus. The Bacillus prodigiosus, which is 

 especially remarkable on account of the development of a red 

 pigment, falls from the air at certain times upon substances 

 containing starch, on which it grows with tolerable rapidity . 

 and it has thus given origin to the legends of showers of blood. 

 The rods are so very short that their long diameter scarcely 

 exceeds their breadth, and for this reason the bacillus wa^ 

 formerly classed with the rnicrococci. The individual rod:-, 

 are motile. On acid nutrient media, however, they expand, 

 according to Rubier, into larger bacilli, which also possess 

 the power of motion. They form spores. On gelatine platen 

 they show even after ten or twelve hours small round 

 granular colonies, which soon liquefy from the surface 



