28o MICRO-ORGANISMS AND DISEASE [chap. 



gelatine due to commencing liquefaction. Looked at 

 obliquely, the gelatine looks pitted by the colonies. As 

 growth proceeds the colony enlarges ; the marginal loops 

 and bundles of twisted filaments project more or less 

 irregularly ; some project for longer, others for shorter dis- 

 tances, sometimes not much beyond the margin of the 

 colony, and the gelatine surrounding the colony becomes 

 more and more liquefied, but remains clear in the liquefied 

 part. In stab cultures made from a culture or from the 

 blood the stab is noticeable after a day or two as a whitish 

 line made up of closely placed dots ; in another day or two, 

 from each dot a lot of fine whitish filaments are seen ex- 

 tending, often like rays from a centre. When the dots are 

 closely placed in linear series the white filaments projecting 

 mostly in horizontal direction from them give to the stab 

 a cliaracteristic appearance, like the vane of a grey feather, 

 the stab being the middle rib ; liquefaction has by this time 

 set in on the surface, i.e. on the upper end of the stab, and 

 there is here a more compact plate-like mass of filaments; 

 the liquefaction gradually proceeds into the depth while the 

 surface patch of the growth increases in bulk ; the liquefied 

 gelatine is clear, and the original surface growth occupies 

 always the deepest part of the liquefied gelatine. When 

 the surface patch while spreading remains adhering to the 

 glass wall of the test-tube, spore formation is observed in 

 the threads of the bacilli, but when the growth is in the 

 depth of the liquefied gelatine no spore formation ever 

 takes place. After ten to fourteen days at 19-20° C. the 

 upper half of the gelatine in the tube is quite liquefied, the 

 liquefied gelatine is clear, and the whole growth is at the 

 bottom of the liquefied part in the form of whitish-grey 

 fluffy masses ; when shaken the mass breaks up into whitish 

 nebulous flocculi. 



