

CONCLUDING EXAMINATION 197 
times disappears as the urine grows cool; but when 
it is considerable, a thick white deposit gradually falls, 
leaving the supernatant fluid quite clear. 
All such deposits of phosphates, however, will 
soon subside after the vessel has been placed in the 
incubator, so that after twelve hours or less we have 
to deal with a clear supernatant fluid in which any 
subsequent turbidity may be easily discriminated. 
In airless vessels, even the first haziness of the fluid 
seems to show itself uniformly throughout the liquid, 
and it is always accompanied by a slight diminution 
of colour. The urine becomes of an appreciably 
lighter shade. When the fermentation is vigorous, 
the haziness of the fluid rapidly passes over to a well- 
marked turbidity, which will generally continue for a 
long time, and without the formation of the slightest 
scum or pellicle on its surface. 
If the fermentation is less vigorous, it may 
manifest itself in one or other of three ways :— 
(a) It may never pass beyond a faint haziness of the 
fluid, even where the vessel is kept in the incubator 
for a week or two;! and in such cases the organisms 
are very scarce, not more than one or two being 
discoverable in any one field of the microscope” A 
11It is possible for an inexperienced observer to confound this 
condition with another in which the fluid remains quite unaltered, but 
in which the glass is attacked and madedim bythe fluid. This occurs 
occasionally when some urines are kept long at a temperature of 122° 
F.; and it is especially apt to occur if the temperature should rise a 
few degrees above this point. 
2 A similar scantiness of organisms is also often met with in the 
blood of certain animals suffering from splenic fever, though in others 
they may swarm abundantly. (Quart. Journ. of Micros. Science, Jan. 
1877, p. 87.) 
