BY R. GREIG SMITH. 343 



Nutrient agar stroke. — A smooth, flat, translucent white growth 

 with a smooth edge. A slightly brownish tinge appears in the 

 upper portion of the slope. 



Saccharose-potato-agar. — A white, moist, slimy growth. 



Potato. — A yellowish, raised, dry-glistening, restricted growth. 

 The medium becomes purplish then brownish. 



Bouillon. — The medium becomes turbid and there is formed a 

 faint surface-ring and a coherent sediment. Indol is produced 

 and nitrates are reduced to nitrites. 



Milk. — The medium is unaltered. 



