
OF PUTREFACTION AND OTHER FERMENTATIVE CHANGES. 337 
above that. This slip is also useful in the stocking of the glass garden. Having 
been taken up from the other glasses, it is placed inverted on the table, so that 
the surface which was downwards during the cooling, and therefore free from 
dust, may be directed upwards. A few drops of the new liquid medium, in 
which development is intended to occur, are then placed upon it with “ heated” 
pipette, and to these a minute portion of the organism is added and diffused 
thoroughly among the fluid by stirring with a “heated” glass rod. The thin 
covering glass being now raised by means of “heated” forceps, aided in the 
manipulations by a “heated” needle, a very small drop of the mixture of 
organism and medium is placed, by means of the pipette, upon the central island 
of the garden, and, in order to ensure a moist atmosphere in the air-chamber, a 
drop of water, which has been boiled, and cooled under protection from dust, 
is introduced with a clean “heated” pipette into the ditch.* The thin covering 
glass, which has been still held in the purified forceps, is then accurately replaced, 
after which its margins are luted down with paraffin, which is conveniently 
melted in an ege-spoon, and applied with a clean steel pen heated from time to 
time in the spirit-lamp. This process requires considerable delicacy and quick- 
ness of manipulation, and constant watchfulness; but with these conditions it 
may be conducted with most satisfactory results; and I have watched one and 
the same organism continuing to grow unmixed in such a garden for several 
weeks together, though carried about with me in a journey made in an autumn 
holiday. 
As soon as the stocking of the garden is completed, it is placed under the 
microscope, and some individual specimens of the organism are sketched by 
camera lucida,—a map, on a smaller scale, being also made with the camera to 
enable the observer to find the objects again. 
On the 11th September I stocked such a garden with a little of the scum 
from the second urine glass, mixed with uncontaminated urine from one of the 
glasses charged on the 10th August, the liquid still retaining its original bright- 
ness and fresh odour. The cells of the scum thus introduced between the 
island and the covering glass were all of the spherical character, as is illustrated 
by the groups at a in Plate XXVI., sketched at 7.20 p.m., within a few 
minutes of their introduction. At 9.50 p.m. the nuclei were found more con- 
spicuous and altered in position, but there was as yet no change of form in the 
* The actual order of proceeding is to introduce the boiled water into the air-chamber first, after 
which the same pipette, being clean, may be at once used for the liquid medium. I have found the 
most convenient form of pipette for these experiments to be a small syringe, having its nozzle connected, 
by means of a short piece of caoutchouc tubing, with a glass tube very narrow and thin, so that it is 
almost instantaneously heated nearly to redness by passing it through a flame, and cools with corre- 
sponding rapidity. The tube is bent near its middle at about a right angle; so that neither the syringe 
nor the hand is held over the experimental glass, while the yielding nature of the caoutchoue junction 
allows the end of the glass tube to be pressed, without risk of breaking, against any object, such as the 
side of a wine-glass, from which an organism is being picked up. 
VOL. XXVII. PART III. 4T 
