THE ORGANISMS OF SUPPURATION. ■ \1\ 



delicate whitish thread to be seen. Very soon this 

 golden film, whilst gradually increasing in size and 

 becoming more intense in colour, sinks deeper and 

 deeper into the slowly liquefying gelatine until after 

 two or three weeks it has almost reached the bottom 

 of the tube. The whitish thread is carried along too, 

 so that finally we see, beneath the golden mass, a 

 white one which gradually becomes yellovy. The 

 cause of this is, that the yellow colouring material can 

 only be formed in the presence of oxygen, and there- 

 fore is absent in the thread, as sufficient air cannot 

 gain access to the bacteria. The manner in which 

 the gelatine is liquefied 'and the colonies slowly sink 

 down, the intense orange-yellow coloration gradually 

 merging into white, all form very characteristic pecu- 

 liarities of this species, by means of which it may be 

 easily recognised from other similar ones. 



On the surface of an agar-agar puncture cultivation 

 a yellow film appears, whilst along the track of the 

 needle a grey or greyish-yellow thread is formed, 

 this gradually diminishes in size as it goes down- 

 wards, but it is still to be distinctly seen, even 

 where no air can gain access to it. Thus we see that 

 we are dealing with a facultative anaerobic organism. 

 If a stroke cultivation be made on agar-agar, a 

 thick layer of a dark golden-yellow colour is formed. 

 Similarly on cooked potatoes a golden-yellow coating 

 is developed. Old cultures of the Staphylococcus 



