MATERIAL FROM THE LIVING SUBJECT 263 
Morgan bacillus are practically identical in appearance, a final iden- 
tification must depend upon their cultm-al characteristics (see page 
353 for table) and their agglutination with specific sera of high potency. 
IVIembers of the mucosus capsulatus group are occasionally found 
in acute and subacute diarrheas. They grow readily upon the surface 
of Endo plates as very viscid, slimy colonies which are readily recog- 
nized by their macroscopic appearance. B. pyocyaneus is an occasional 
incitant of intestinal disturbance. Its colonies upon ordinary agar 
are surrounded by a yellowish or greenish halo. The same general 
appearance characterizes its growth upon Endo medium. Among the 
anaerobic bacilli, the "gas bacillus" (B. aerogenes capsulatus) is the 
most important. The organism is present in variable but small num- 
bers in the feces of healthy adults, and occasionally in the dejecta of 
young children as well. It may at times become a very prominent 
organism among the fecal flora. The isolation and recognition of the 
gas bacillus from the intestinal contents depends primarily upon the 
energetic fermentation which it excites in milk cultures inoculated with 
feces and heated to 80° C. for twenty minutes prior to incubation. 
(See Chapter XXR" for details.) Members of the spiral group, includ- 
ing the highly pathogenic cholera vibrio, are readily isolated and iden- 
tified by the procedure described in the section on Vibrio cholerae 
(Chapter XXV). 
Tubercle bacilli are not infrequently found in the feces of indi- 
viduals who have advanced pulmonary tuberculosis. It is almost 
certain that the organisms have been swallow^ed in a majority of such 
cases. Occg^sionally a diagnosis of tuberculosis may be made thus in 
young children from whom it is difficult or impossible to obtain a 
satisfactory specimen of sputum. Tubercle bacilli are also found in 
the feces, derived from tuberculous ulcerations of the intestinal mucosa. 
A diagnosis of tubercle bacillus cannot safely be made from a demon- 
stration of acid-fast organisms in the fecal contents, however, because 
acid-fast bacteria other than tubercle bacilli may be present. Tubercle 
bacilli may be obtained practically free from other intestinal bacteria* 
by careful treatment of the feces with antiformin. This substance 
dissolves the non-acid-fast bacteria, leaving the acid-fast organisms 
intact and viable. A guinea-pig furnishes the only reliable method 
of distinguishing tubercle bacilli from adventitious non-pathogenic 
acid-fast organisms. 
Examination of Sputum, of Buccal and Pharyngeal Material. i— A 
sample of sputum suitable for bacteriological examination should be 
collected with care. The mouth should be clean, the receptacle should 
be sterile, and the material should be raised by a deep pulmonary 
cough, not by a superficial efi'ort. Buccal and pharyngeal material 
for bacteriological examination is usually obtained upon sterile cotton 
swabs. Bits of membrane may be removed with sterile forceps. 
1 An excellent discussion of Infections of the Respiratory Tract and of Sputum as a 
Means of Diagnosis is that of Leutscher (Arch. Int. Med., 1915, 16, 657). 
