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 polar 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 LofHer'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 



