DIPHTHERIA. 299 



especially in scarlet fever, the streptococcus appeared to be 

 the predominant and characteristic organism. 



These rods described by Klebs and Loffler vary much 

 in length, but they average from 3 to 6p, ; they are straight 

 or slightly bent, one end or both sometimes being a little 

 swollen. There may be deeply stained or bright glistening 

 points in the protoplasm, though these are not usually met 

 with. Babes indeed describes spores as occurring in the 

 diphtheria bacillus, but, as is mentioned later, these are not 

 real endospores but consist merely of altered protoplasm. 



In order to stain the bacillus it is only necessary to remove a small 

 fragment of the false membrane by means of a piece of absorbent cotton 

 wool tied firmly to a pair of forceps or to a pen holder ; from this it is trans- 

 ferred to a scrap of blotting-paper, and thence to a cover glass, where it is 

 broken down as finely as possible, heated over a flame in the ordinary 

 fashion, and stained with Loffler's alkaline methylene blue, or by Gram's 

 gentian violet method (washing thoroughly with water before attempting to 

 examine), or by a method adopted by Roux and Yersin, who use a blue, com- 

 posed of equal parts of aqueous solution of violet dahlia and methyl green, 

 with water added until a clear, but not too deep, blue is obtained. A drop 

 of this is placed on the slide, the cover glass on which the fragments are 

 dried is inverted and lowered on to it, the superfluous fluid is removed with 

 a piece of blotting-paper, and the organism is examined at once. 



The vital characteristics of the organism may be used in separating it 

 from false membranes, even where contamination from the organisms of the 

 mouth and pharynx has occurred ; and it is recommended that in order, 

 wherever there is any doubt, to be absolutely certain of the diagnosis of 

 diphtheria, cultivations on blood serum should be made. 



The specific diphtheria bacilli appear to be stained more 

 readily and more deeply than any of the organisms that 

 usually accompany them. They occur in small groups, as 

 short, straight, or curved rods, with ends sometimes pointed, 

 sometimes curved ; they are never absent from cases of true 

 diphtheria in the early stages, and in some cases the 

 membrane consists of an almost pure cultivation of the 

 bacillus. In older cases, however, the organisms do not 

 stain so equally ; many pear-shaped and club-shaped bacilli 

 are present, and, in some very old membranes, it is difficult 

 or impossible to distinguish any characteristic bacilli, the ac- 

 companying organisms becoming more numerous, especially 

 as the surface becomes foetid and softened. In such cases the 

 specific organisms can only be found entangled in the 

 deeper fibrinous net-work. 



Roux and Yersin hold that microscopic examination gives the most precise 



