18 LABORATORY BACTERIOLOGY 
in suspension, the quantity and nature of sediment, and the 
presence or absence of a membrane. The reaction of the 
liquid should be taken and its consistence noted. The odor 
“should be determined. In agar cultures the extent of the 
growth (feeble, moderate, or vigorous), its color, form, and 
surface appearance (dull or glistening), should be observed. 
The character of the growth in the condensation water should 
also be noted. In stab cultures the appearance of the growth 
both on the surface and along the needle track should be 
described. In gelatin the absence or the presence and extent 
of liquefaction should be noted in addition to the features 
already referred to for the stab-agar cultures. (See Chester’s 
terminology, §§ 31 and 51.) 
27. Testing the reaction of liquid cultures. Place a small 
piece of each of the red and blue litmus papers in a solid 
watch glass. With the platinum loop carefully place a drop 
of the culture on each piece of the paper. After recording 
the reaction produced, — neutral, acid, or alkaline, with the 
degree, — cover the paper with a disinfectant (a solution of 
corrosive sublimate 1 to 1000). After it has acted for about 
10 minutes, empty it with the paper into the waste jar and 
wash the watch glass. 
28. To determine the viscidity. (a) Bouzllon cultures. 
Insert the platinum loop into the liquid and carefully with- 
draw it. The approximate degree of viscidity may be deter- 
mined by the extent of the adhesion of the liquid to the loop 
and by the length of the threadlike filament drawn out. By 
gently shaking the tube, a viscid sediment will rise up, appear- 
ing as a somewhat twisted, tenacious cone with its apex 
reaching to or near the surface. A friable sediment will break 
up and become disseminated through the liquid upon agita- 
tion. (4) Agar and gelatin cultures. Touch the surface 
growth with the end of the platinum needle, and if it is viscid, 
a threadlike string will be drawn out. Note whether the 
growth is pasty or friable. 
