STAPHYLOCOCCUS PYOGENES A UK E US. 



167 



turbid. Ultimately liquefaction extends out to the wall of 

 the tube (Fig. 46). In gelatine plates colonies may be seen 

 with the low power of the 

 microscope in twenty -four 

 hours, as little balls some- 

 what granular on the surface 

 and of brownish colour. On 

 the second day they are 

 visible to the naked eye as 

 whitish-yellow points, which 

 afterwards become more 

 distinctly yellow. Lique- 

 faction occurs around these, 

 and little cups are formed, 

 at the bottom of which the 

 colonies form little yellowish 

 masses. On agar, a stroke 

 culture forms a line of 

 abundant opaque growth, 

 with smooth, shining surface, 

 well formed after twenty-four 

 hours at 37 C. Later it 

 becomes bright orange in 

 colour, and resembles a streak 

 of yellow oil paint. Single 

 colonies on the surface cf 

 agar are circular discs of 

 Similar appearance, which gelatine, (a) 10 days old, (b) 3 weeks 

 may reach 2 mm. or more old. Showing liquefaction of the 

 in diameter. On potatoes it 

 grows well at ordinary tem- 

 perature, forming a somewhat abundant layer of orange 

 colour. In boui/lon it produces a uniform turbidity, which 

 afterwards settles to the bottom as an abundant layer which 

 assumes a brownish-yellow tint. In the various media it 

 renders the reaction acid, and it coagulates milk, in which 

 it readily grows. The cultures have a somewhat sour odour. 

 It has considerable tenacity of life outside the body, 



characters f growth ' 



