918 The American Naturalist. [November, 
extremely small quantity of hydrochloric acid. In this the 
color rapidly disappears, especially if the fluid is stirred with 
a glass rod. At the end of a very short time, the length of 
which varies in different cases, certain parts will be seen to 
have preserved their color, if the disease is present, while the 
rest of the section has already bleached. The sections must 
now be removed immediately to a dish of pure, anhydrous 
spirits of turpentine, in which they are left until thoroughly 
penetrated by the liquid. They may then be examined directly 
or first mounted in Canada balsam, after which they may be 
kept indefinitely. When the work has been well done the 
sections will be brown in those parts which contain the bacteria 
and which were originally yellow, while in all other parts they 
are colorless. 
(2) Gelatin—The culture media was made by adding to 
water containing glucose and a little meat extract, enough 
gelatin to give a solid, clear yellow, perfectly transparent 
mass at ordinary temperatures. This was sterilized by 
heating from time to time to 100° C. It was then carefully 
pipetted into tubes which were plugged with cotton, and re- 
sterilized by heating every day to 100° C., for some days. 
Pipettes, tubes and cotton plugs had previously been heated 
to 140° C. Tubes prepared in this way were unplugged, in- 
fected with bacteria taken from a diseased bulb (the transfer 
being made by means of a platinum wire previously heated to 
redness), quickly closed, and then left at the ordinary room 
temperature. The organism makes a good growth on gelatin. 
The gelatin is readily and completely liquefied. 
“ Experiment of June 12, 1885.—The above described opera- 
tions were made this day, and two days later I saw in all the 
tubes the gelatin liquefy under the influence of the bacteria. 
Examination showed that the part not yet liquefied also con- 
tained bacteria, so that the latter must first penetrate into the 
gelatin and then cause its liquefaction. The formation, in the 
part of the gelatin which is still solid, of white globules con- 
sisting entirely of bacteria, served to make this fact very appar- 
ent. Bubbles of gas which can only arise from the action of 
these organisms also developed in it continually. After a short 
