202 PATHOGENIC BACTERIA.

organisms. Wertheim cultivated the gonococcus from a
case of chronic urethritis of two years' standing, and
proved its virulence by producing with it gonorrhea in
a human being. The organisms are generally found
within the pus-cells (Fig. 58) or attached to the surface
of epithelial cells, and should always be sought for as
diagnostic of gonorrhea, especially as urethritis some-
times is caused by other organisms, as the Bacillus coli
cornmunis1 and the Staphylococcus pyogenes.

The cultivation of the gonococcus is not an easy task,
but one which requires considerable bacteriologic skill.
Wertheim accomplished it by diluting a drop of the pus
in a little liquid hitman blood-serum, then mixing this
with an equal part of melted 2 per cent, agar-agar at 40°
C., and pouring into Petri dishes. As soon as the media
became firm the dishes were stood in the incubator at
37° C., and in twenty-four hours the colonies could be
observed. Those upon the surface showed a dark centre,
around which a delicate granular zone could be made
out.

When one of these colonies is transferred to a tube of
human blood-serum or the above mixture obliquely co-
agulated, isolated little gray colonies occur; later these
become confluent and produce a delicate smeary layer
upon the medium. The main growth is surrounded by
a thin, veil-like extension which gradually fades away
into the medium. A slight growth occurs upon the
water of condensation,

Turro says that the gonococci may also be cultivated
upon acid gelatin, upon gelatin containing acid urine,
and also in acid urine itself, in which the gonococci grow
near the surface, while the pus-cocci which may be mixed
with them sink deeper into the medium. His work has
not been confirmed by other investigators.

Heiman,2 who made an extensive series of culture-ex-

1 Van der Pluyn and Loag: Centralbl f. Bakt. u. Parasitenk., Bd. xvii.,
Nos. 7, 8, Feb. 28, 1895, p. 233.

2 Med. Record, Dec. 19, 1886.