650 BACTERIA OF THE SURFACE OF THE BODY 
McFarland (1895) says that in his researches the microdrganisms 
found were for the most part “those already described by others and 
of common occurrence in the air.” He encountered, however, sev- 
eral bacilli not previously described (“Bacillus hirsutus, Bacillus 
coerulefaciens, Bacillus circumscriptus, Bacillus succinacius, Bacillus 
violaceus flavus”). Lachowicz (1895) failed to obtain any bacteria 
in his cultures from the conjunctival sac in sixty-nine per cent of the 
healthy eyes examined by him (sixty-three eyes in all). He con- 
cludes that the microédrganisms, which at times are found in the 
healthy conjunctival sac, come principally from the air; that they 
are present in small numbers and probably remain only for a short 
time. His experiments show that most species when artificially 
introduced rapidly diminish in numbers and soon disappear entirely. 
Cultures of Streptococcus pyogenes and of Bacillus xerosis conjunc- 
tives introduced into healthy eyes did not cause the slightest irrita- 
tion. In this connection we may remark that the same is true as 
regards pathogenic bacteria introduced into the bladder, but that 
when there is some cause of local irritation or injury a chronic 
cystitis is likely to be developed. In like manner, we believe, chronic 
conjunctivitis may be developed as the result of local irritation in 
connection with the presence of pathogenic bacteria and especially of 
the pyogenic micrococci. 
The extended researches of Bach (1894) gave results corresponding 
with those of previous investigators, and not with those reported by 
Lachowicz, who, as stated above, failed to obtain cultures from sixty- 
nine per cent of the healthy eyes examined. Bach says: “In a large 
percentage of the cases the presence of bacteria may be demonstrated, 
even when the conjunctiva presents a perfectly normal appearance; 
the conjunctival sac must therefore be regarded as constantly in- 
fected.” Bach describes twenty-seven different microdrganisms ob- 
tained by him in pure cultures from this source, of these eighteen 
are micrococci. Herecognizes the fact that most of them come from 
the air, while others are introduced by the hands in rubbing the 
eyes, etc. In diseased conditions these are more numerous than in 
health, but the pus cocci are not infrequently found in healthy eyes. 
As bacteria are constantly present in the air, they are necessarily 
deposited upon the moist mucous membrane of the nose during in- 
spiration. Indeed, it would appear as if an important function of 
this extended mucous membrane is to purify the air from suspended 
particles, and it has been shown by experiment that expired air is 
practically free from bacteria. The greater number of those con- 
tained in inspired air are deposited upon the mucous membrane of 
the anterior nares. In culture experiments made by Von Besser, 
Wright, and others the aasal mucus was found to contain a great 
