54 



DE. BASTIAN OK THE 



fluid may be observed during the preliminary boiling over the 

 flame, though after the closed vessel has been boiled in the can 

 the fluid may be distinctly troubled, especially where the period 

 of heating has been prolonged. When the cloudiness is very 

 slight, it sometimes disappears as the urine grows cool ; but when 

 it is considerable, a thick white deposit gradually falls, which leaves 

 the supernatant fluid quite clear. In cases where no phosphates 

 have been deposited by the process of heating, this event may 

 possibly occur on the breaking of the liquor-potassas tube — though 

 it will not often happen, if the amount of liquor potassaa added 

 does not suffice actually to neutralize the urine in the experi- 

 mental vessel. 



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 discrimi- 

 minated. 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 fermenta- 

 tion 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 t. A change of this kind is also 

 often late in manifesting itself, (b) The fluid itself may remain 

 perfectly clear ; but at the sides of the vessel, or on some phosphatic 

 sediment at the bottom, one, two, three, or more little whitish 

 tufts may show themselves, which continue to increase in size for 



* It 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 made dim by the 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. 



t A similar scantiness of organisms is also often met with in the blood of 

 certain animals sufiering from splenic fever, though in others they may swarm 

 abundantly. (Quart. Journ of Micros. Science, Jan. 1877, p. 87.) 



