14 BACTEEIOLOGY OF THE EYE 



show this. Where the safranin is of medium intensity the bacilli are 

 dark red and the capsules light red. In overstained preparations 

 the capsule is so dark that the bacillus appears to be very thick. At 

 places where the film has been too much heated the capsule is shrunk, 

 with a clear space around it, but the red membrane can still be seen 

 closely surrounding the bacillus. In many cultures clear spaces will 

 be noticed where the film has been overheated, and still the bacilli 

 are kept discrete by a faintly-stained membrane. 



The Diplobacillus possesses not nearly so definite a capsule. 

 Using special stains, as did Bietti and Agricola (and Macnab for 

 Diplobacillus of Petit) in my laboratory, an ectoplasm is readily seen, 



FIG. 3. Pus FROM LACRYMAL SAC CONTAINING FRIEDLANDER'S PNEUMOBACILLI ; 

 ALSO IN a, B. XEROSIS ; IN b, B. INFLUENZA. 



The capsules of the Pneumobacilli appear clear in and red in b (safranin overstain), 

 a few Pneumococci bine. 



but it generally does not show any considerable width. In Gram 

 (balsam) preparations the appearance of the capsule is very inconstant, 

 and in many cases entirely fails, so that here we have a ready means 

 of differentiating the Pneumobacillus. 



In preparations stained with simple aniline dyes and examined in 

 water, the clear envelopes are more numerous and more visible, as is 

 the case in photographs. 



It is quite correct, as Gifford stated, that the Diplobacillus has a 

 capsule. In the differential diagnosis it must be emphasized that in 

 Gram preparations especially the capsule is not marked. I have never 

 seen stained capsules in a preparation made by this method and 



