MATERIAL FROM THE LIVING SUBJECT 265 
blood-agar plates are the most satisfactory media to employ." Hemo- 
lytic streptococci, pneumococci, Pneumococcus mucosus and influenza 
bacilli grow upon this medium. 
Diphtheria bacilli are grown upon Loffler's blood serum, as described 
in the section on Diphtheria. 
Tubercle bacilli can be readily distinguished from lepra bacilli, 
nasal secretion bacilli and adventitious acid-fast organisms by the 
injection of washed, cheesy particles from sputum into guinea-pigs. 
The tubercle bacillus is extremely pathogenic for this animal; the 
other acid-fast bacilli are not pathogenic. 
The organism commonly found in Vincent's angina (B. fusiformis) 
is not readily cultivated upon ordinary media, although it may be 
grown anaerobically." Its recognition usually depends upon its 
demonstration in smears prepared directly from the lesions. 
Bacteriological Examination of the Eye.— The normal conjunctival 
sac frequently contains Staphylococcus albus and B. xerosis; indeed 
these organisms are so commonly found in this region that they are 
regarded as normal inhabitants. Abnormally a variety of bacteria 
may develop on the conjunctiva, frequently causing violent inflam- 
mation. INIaterial for bacteriological examination is best obtained 
after gently flooding the conjunctival sac with a few drops of sterile 
salt solution, which are removed with a sterile cotton swab. Then 
a small sterile cotton swab is gently rubbed over the conjunctival 
surface and inoculated into suitable media after a Gram-stained smear 
has been made and examined. 
The gonococcus, Koch-Weeks bacillus, and the pneumococcus are 
more commonly the incitants of acute inflammation of the conjunc- 
tiva; less frequently hemoglobinophilic bacilli (B. influenzae particu- 
larly) or B. pyocyaneus may be found. An examination of Gram- 
stained smears will indicate the media to be employed if isolation of 
the organisms in pure culture is desired. The meningococcus is 
occasionally found in conjunctival inflammations in cases of cere- 
brospinal meningitis; it must not be confused with the gonococcus. 
Micrococcus catarrhalis, which resembles both the gonococcus and 
meningococcus in its morphology and staining reactions, does not 
produce an acute conjunctival inflammation with a profuse purulent 
discharge— rather, this organism usually gives rise to a slight reaction, 
even though the organisms are numerous.^ Blood-agar plates are 
preferable for the cultivation of bacteria from the eye. Not only 
do the hemoglobinophilic organisms and the gonococcus grow in this 
medium— the less fastidious forms also develop rapidly. 
' Several drops of sterile blood, obtained from the finger or the lobe of the ear after 
a preliminary sterilization, are placed in the center of an agar plate. The material 
to be studied is streaked out radially from the blood. Enough blood can be moved 
with the organisms by this method to insure growth. The agar should be sugar-free. 
- Varney: Jour. Bacteriol., 1927, 13, 275. 
' For a discussion of Gram-negative diplococci found in the eye, see Blue (Arch. 
Ophthalmol., 1915, 44, No. 6). 
