G74 WEST OF SCOTLAND VETERINARY MEDICAL ASSOCIATION. 
The true tubercular pus is thin, turbid, yellowish-white in 
colour, with portions of cheesy matter intermixed, or floating in 
it, inodorous, and having small cells of an irregular shape, and 
without a distinct nucleus. 
Microscopically .—Tubercle is found to consist of corpuscles, 
irregular in outline and size, having in their interior granular or 
molecular matter, with granular matter scattered between the 
corpuscles, and, according to Bennett, possessing neither nucleus 
nor nucleoli; but I have myself, in company with Professor 
Williams, seen true nuclei in tubercle from the brain of a calf (to 
which case I shall have hereafter to refer), very much resembling 
that from the same situation figured by Virchow, and in rare 
cases only having fibres interwoven with the corpuscles. 
Tubercular formations differ from those of cancer, although 
probably, in some instances, traceable to similar causes, in being 
more rapid in growth; by their tendency primarily to attack 
lymphatic glands, by being encysted, softer, and non-fibrous; by 
not having so great a tendency to spread to surrounding tissues 
other than those in which they first make their appearance; by not 
possessing the corded processes so indicative of cancer, by attack¬ 
ing animals of all ages, and having no reproductive powers when 
extirpated. The pus of cancer is thinner, more ichorous, and 
irritative; the cells of cancer are larger, surrounded by a fibrous 
stroma, assume any shape, and are filled with perfectly formed 
young ones. The cells of pus also are larger than those of 
tubercle, rounder, more regular in outline, and when acetic acid 
is added show a well developed nucleus or nucleoli. 
The ulcers of tubercle, when appearing in the skin, are 
characterised previous to their external irruption by the sub¬ 
cutaneous structures becoming glued to the enveloping dromis, 
and remaining closely adherent to it even when the ulcer is 
healed; the skin also becomes extensively undermined and 
thinned. The edges of the ulcer after irruption are thin, 
tapering, and irregular: this kind of ulceration is most frequently 
seen in dogs. In ulceration of mucous membrane the pressure 
of the growth causes gradual absorption and thinning, allowing 
of the escape of the tuberculous matter through the orifice, with 
the yellow appearance of the tubercle plainly visible in the 
opening. We never have the soft, inverted, jagged edge of cancer 
or its livid colour and fumigoid, cauliflower granulations, but we 
occasionally have sinuous external openings, in some instances, 
two or three to one tumour. 
Tubercle may exist, and frequently does, as one immense mass, 
or scattered throughout the whole system in a number of masses, 
collectively many pounds in weight. Cancer is more frequently 
solitary, and increases very slowly. 
