80 BACTERIOLOGICAL DIAGNOSIS. 
not decolorised a fresh specimen should be prepared 
and immersed in the acid for a longer period. 
ACTINOMYCOSIS. 
Actinomycosis is very closely allied to tuberculosis ; 
the lesions appropriate to the two diseases are almost 
identical in histological appearance, and the granuloma 
which occurs in actinomycosis goes on to fibrosis or to 
the formation of ‘‘cold abscesses’’ just as a tubercle 
may do. The formation of fibrous tissue is most 
marked in cattle, and in them the disease is more 
chronic ; suppuration is more common in man, and the 
disease runs a more rapid course. 
The pus from an actinomycotic abscess is often viscid 
and contains a greater or smaller number of small 
greenish, yellow, or brownish nodules. They are about 
as large as the head of a very small pin, and are quite 
opaque; under the low power of the microscope such 
a granule has a coarsely granular appearance, and looks 
something like a raspberry. If nodules presenting these 
appearances are found in any specimen of pus, whatever 
be its origin, a careful microscopic examination should 
be made to determine its nature. This is not difficult. 
Method.—Place some of the pus which contains these 
granules on a clean slide and press another slide upon 
it'so as to crush the granules, dry, fix, and stain by 
Gram’s method. 
Tumours removed or incised at an operation, or 
organs removed at a post-mortem examination, should 
have their cut surfaces rubbed upon the surface of a 
slide and the film thus obtained treated in a similar 
