150 Anmuil Eeport of the Eoyal Veterinary College on 
lesions have to be locali-ed, or if their extent in an organ has to be noted, slices 
or " sections " of exceedino' thinness are cut from it by means of a Hamilton- 
Bruce microtome ; this instruaieut enabling us to obtain them of any size up 
to 13 X 9 inches, . . . 
These sections, after being: submitted to the action of Tarious staining 
reagents, whereby the diseased portions are differentiated from the healthy, 
are mounted between two thin glasses and transferred to the microscope 
room for examination; but it should beiiept in mind that such large sections 
are not always required, and as a rule much smaller ones, which can be cut 
about the ^ part of an inch in thickness, are sufficient for all pracUcal 
purposes. 
The whole of the foregoing, and also such work as modelling in plaster, 
■wax, and gelatine, is carried on in the preparation room, and from it is 
Fig. L— Jar for Collection of Organisms from Atmosphere. 
b 
air jar ; 6, perforated rubber cap ; c, elbow tubes ; d, eihanst tube ; e, litre flask 
with (/) tube leading from it. 
reached the microscope room. Here the sections are placed under suitable 
lenses, and the results of such obseryation are recorded. Frequently photo- 
graphy, both with the ordinary camera and with the microscope and camera 
combined, is called into aid in this important matter. Fig. 3 illustrates 
the almost unique and expensive apparatus employed for photo-micrography. 
It was made by Messrs. Swift & Son from designs and under the super- 
intendence of Mr. A. Pringle, of Bexley Heath ; it is fitted with the oxy- 
hydrogen light of about 000 candle-power, and may be used to obtain 
enlargements up to about 4,000 diameters. 
In this room is stored the apparatus not in actual use, and also some 
which is kept ready for emergencies. 
A jar, which is of peculiar construction, and is used for the collection of 
organisms from the atmosphere, is worthy of notice (fig. 4). The bottom 
of this jar is covered with a layer of peptonised gelatine, which has been 
