MILLERS SPIRILL UM. 369 



be detected upon very careful examination. (See a, Fig. 

 75.) When located deep in the gelatin the colonies 

 are round, sharply circumscribed, of a pale-yellowish or 

 greenish-yellow color, and marked by very delicate 

 irregular lines or ridges. After forty-eight hours the 

 plate containing many colonies is entirely liquefied, 

 while that containing only a few shows the presence of 

 round, sharply cut, shallow pits of liquefaction that 

 measure from two to ten mm. in diameter. They are 

 a little denser at the centre than at the periphery, and 

 the dense centre is not sharply circumscribed, but fades 

 off into what has the appearance of a delicate film. 

 (See 6, Fig. 75.) As the colonies become older they 



FIG. 75. 



6 

 Colonies of Miller's spirillum on gelatin, at 20 to 22 C. X about fifty-seven 



diameters. 



a. Colony just beneath the surface of the gelatin. 6, Colony on the surface 

 of the gelatin. 



are sometimes marked by irregular radii extending from 

 periphery to centre like the spokes of a wheel. 



In stab cultures in gelatin it rapidly produces lique- 

 faction, both at the surface and along the needle-track, 

 and in most respects gives rise to a condition very like 

 that resulting from the growth of Finkler and Prior's 

 spirillum, though differing from it in certain details. 

 (See a, b, c, d, Fig. 76.) 



On agar-agar nothing of special interest appears as a 

 result of its development. 



