108 BACTERIOLOGICAL DIAGNOSIS. 
and in the internal organs. It does not stain by Gram’s 
method, and when stained by other processes it often 
exhibits a characteristic polay staining, the ends of the 
‘bacillus being coloured deeply, whilst the intervening 
portion remains colourless (Plate II., fig. 4). It might 
be mistaken for a diplococcus; it could not be mistaken 
for the pneumococcus (to which it has some resem- 
blance) as that organism stains by Gram. Degenerate 
forms which resemble cocci, &c., often occur in cul- 
tures, but are seldom met with in the body during 
life. , 
The diagnosis may be made by an examination of 
fluid aspirated from the bubo or of the blood. In 
bubonic cases the former method should always be 
adopted, as the bacilli are present therein in vast 
numbers and generally in pure culture; the amount of 
fluid which has to be removed is very small, even if 
cultures have to be taken. 
When this is not the case two films should be made 
in the way already described, fixed and stained, the 
one by dilute carbol-fuchsin or Léffler’s blue and the 
other by Gram’s method. If the bacilli are present 
they will appear as short oval rods which may or may 
not exhibit the polar staining; if the specimen has been 
stained for the proper length of time (about 2 minutes) 
most of them will do so, but in any case it will most 
likely be present in a few. The Gram specimen will 
not show these rods; there may be a few pus cocci 
present as a secondary infection. 
The blood is examined by any of the methods to be 
described subsequently, and a very careful search made, 
as the numbers of the bacilli may be comparatively 
scanty. 
If a careful examination of stained films made from 
