296 BACTERIA IN CROUPOUS PNEUMONIA. 



7. BACILLUS OF FRIEDLANDER. 



Synonyms. Pneumococcus (Friedlander); Bacillus pneumonias 

 (Fliigge). 



Obtained by Friedlander and Frobenius in pure cultures (1883) 

 from the exudate into the pulmonary alveoli in cases of croup- 

 ous pneumonia. Subsequent researches show that it is only present 

 in a small proportion of the cases nine times in one hundred and 

 twenty-nine cases examined by Weichselbaum, three times in seventy 

 cases examined by Wolf. 



Morphology. Short rods with rounded ends, often so short as 



to resemble micrococci, especially in very 



($JM recent cultures ; commonly united in pairs 



^ ^ ^(^/^ or chains of four, and under certain cir- 



^0o Q ^(o) ffi cumstances surrounded by a transparent 



Ji j{ capsule. The gelatinous envelope so- 



FIO. 88. -Baciiiusof Friedlander; called capsule is not seen in preparations 



o, from a culture; 6, from blood of ma d e f rom cultures in artificial media, but 



mouse, showing capsule. (Fliigge.) . . . 



is very prominent in properly stained prepa- 

 rations from the blood of an inoculated animal. It often has a diame- 

 ter equal to or greater than that of the enclosed cell, and appears to 

 consist of a substance resembling mucin, which is soluble in water or 

 dilute alcohol. Where several cells are united in a chain they may 

 all be enclosed in a common envelope, or each may have its own cap- 

 sule. This capsule is not peculiar to Friedlander's bacillus, as he 

 at first supposed, but is found in other bacilli and also in the writer's 

 Micrococcus Pasteuri. 



Friedlander's bacillus stains readily with the aniline colors, but 

 is decolorized by the iodine solution used in Gram's method. In 

 preparations from the blood of an inoculated animal, stained by an 

 aniline color, the capsule appears as an unstained envelope surround- 

 ing the stained cell, but by special treatment the capsule may also be 

 stained. Friedlander's method is as follows : The section or cover- 

 glass preparation is placed for twenty-four hours in a solution of 

 gentian violet and acetic acid, containing fifty parts of a concentrated 

 alcoholic solution of gentian violet, one hundred parts of distilled 

 water, and ten parts of acetic acid. The stained preparation is 

 washed for a minute or two in a one-per-cent solution of acetic acid, 

 dehydrated with alcohol, cleared up with oil of cloves or cedar, and 

 mounted in balsam. The bacillus is quickly stained in dried cover- 

 glass preparations by immersion in aniline- water-gentiaii-violet solu- 

 tion (two or three minutes). The stained preparation should be de- 

 colorized by placing it in absolute alcohol for half a minute, and then 

 washed in distilled water. 



