, so forming an extensive surface of medium extending from the
bottom of the tube almost to its mouth.

This is employed for "streak" or "smear" cultivations (_Strichcultur_).

2. Straight tube (Fig. 119), in which the medium forms a cylindrical
mass in the lower portion of the tube and presents an upper surface
which is at right angles to the long axis of the tube.

This is employed for "stab" or "stick" cultivations (_Stichcultur_), or
by inoculating the medium whilst fluid, and allowing to solidify in this
position, for "shake" cultivations.

_Streak Culture._--

1. Flame the plugs, sterilise the platinum loop (or spatula). Open the
tubes and charge the loop as in previous inoculation.

2. Pass the infected loop to the bottom of the tube to be inoculated and
draw it, as lightly as possible, along the centre of the surface of the
medium, terminating the "streak" over the thin layer of medium near the
mouth of the tube.

3. Replug the tubes, sterilise the platinum loop.

4. Label the newly inoculated tube and incubate.

_Smear Culture._--Proceed generally as in streak culture, but rub the
infected loop all over the surface of the medium, instead of restricting
the inoculation to a narrow line.

NOTE.--Gelatine and agar oblique tubes should be freshly
"slanted" before use.

_Stab Culture._--

1. Flame the plugs, open the tubes, sterilise the platinum needle and
charge it with the inoculum as in the previous cultivations.

2. Pass the platinum needle into the tube to be inoculated until it
touches the centre of the surface of the medium. Now thrust it deeply
into the substance of the medium, keeping the needle as nearly as
possible in the axis of the cylinder of medium. Then withdraw the
needle.

3. Replug the tubes. Sterilise the platinum needle.

4. Label the newly planted tube and incubate.

NOTE.--When gelatine is stored for some time the upper
surface of the cylinder becomes concave owing to
evaporation. Tubes showing this appearance should be
liquefied and again allowed to set before use for stab
culture, otherwise when the needle enters the medium, the
surface tension will cause the gelatine cylinder to split.

[Illustration: FIG. 118.--Sloped or slanted medium for streak or smear
culture.]

[Illustration: FIG. 119.--Straight tube.]

_Shake Culture._--

1. Liquefy a tube of nutrient gelatine (or agar, or other similar
medium), by heating in a w