650 BACTERIA OF THE SURFACE OF THE BODY 



McFarland (1895) says that in his researches the microorganisms 

 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 

 ccerulefaciens, Bacillus circurnscriptus, Bacillus succinacius, Bacillus 

 violaceus flavus"). Lachowicz (1895) failed to obtain any bacteria 

 in his cultures from the con junctival sac in sixty-nine per cent of the 

 healthy eyes examined by him (sixty-three eyes in all). He con- 

 cludes that the microorganisms, 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- 

 tive 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 microorganisms ob- 

 tained by him in pure cultures from this source, of these eighteen 

 are micrococci. He recognizes 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 nasal mucus was found to contain a great 



