6 GENERAL BACTERIOLOGY LESSON 



provided the pipette was fine enough, the deeper part of 

 the gelatine only is inoculated. 



Keep the tube at the ordinary temperature of the 



room exposed to diffused light. 



Gradually a whitish growth appears in the depth of 

 the gelatine, which slowly extends to the surface 

 and eventually breaks through. It will now 

 quickly develop its typical red pigment. 



(5) Inoculate a potato tube with Aspergillus niger by 

 rubbing the material thoroughly over the slanting surface. 

 Keep the tube in the cool incubator at 20 C. 



Examine after forty -eight hours: a white mould 

 will be found on the surface of the potato. Later 

 on a few black spots will appear on the white 

 surface, and after a few weeks the whole growth 

 will be black. 



(6) Make an agar-agar streak culture of the Bacillus 

 fluorescens and keep the tube at 20 C. 



Examine next morning : a copious growth has 

 developed on the surface of the agar-agar and the 

 culture medium has assumed a light green tint. 



(7) Make a gelatine streak culture of Torula alba and 

 keep the tube at 20 C. 



Examine after forty-eight hours : there is no lique- 

 faction of the culture medium. 



(8) Make a gelatine stab culture of Sarcina lutea and 

 keep it at 20 C. 



Examine after forty-eight hours : there is a slight 

 yellow growth with commencing liquefaction of 

 the gelatine. 



