BY R. GREIG SMITH. 



127 



Bouillon. — At first there appears a slight turbidity, which, 

 while increasing, slowly gravitates, leaving the upper portions 

 clear, the middle layers turbid, and a voluminous flocculent white 

 precipitate at the bottom of the medium. A film grows upon the 

 surface, and after a time becomes indented in places. There is 

 no indol produced. 



Potato. — A dry white layer is formed, which slowly spreads 

 over the surface. It remains flat, and is never raised, puckered, 

 nor wrinkled when grown at 22°. At 30° a slight wrinkling may 

 appear. The centre becomes of a slightly brown tinge, and in 

 the old cultures (12 days) this brown colour has spread over the 

 expansion. 



Blood serum. — A spreading grey-white layer is formed on the 

 solidified serum. The margin of the growth is irregular and 

 bristly when viewed with a lens. The serum is not liquefied. 



Milk. — The casein is first coagulated and then dissolved. 



Germination. — For observing this process an old agar culture 



o O O CO CD 



a 3c so 



--•//A^ 



Germination of three spores in nutrient gelatine ; the numbers indicate 

 the times of observation. 



was sown in gelatine and a loopful smeared over a sterile cover- 

 glass, which was then inverted over a hollow glass slide. The 



