120 THOMPSON YATES LABORATORIES REPORT 
Maerthen 10 described sixteen varieties of cocci, and two of bacilli ; the cocci 
included staphylococcus aureus and albus. Streptococcus was not found. 
MacFarland says that the micro-organisms found in the normal sac are of 
common occurrence in the air. He encountered several bacilli not previously 
described (Bac. hirsutus, Bac. coerule-faciens, Bac. circumscriptus, Bac. succinatus, 
Bac. violaceus flavus). 
Lachowicz* examined sixty-three normal conjunctival sacs, of which sixty- 
nine per cent, were sterile. He concluded that the micro-organisms present came 
principally from the air, and that they only stayed there a very short time. In his 
experiments he showed that pure cultures of streptococcus and xerosis bacilli 
introduced into the conjunctival sac did not produce the slightest irritation. Staphy- 
lococci were also found. 
Gifford, in his cases, found exclusively micrococci. 
Bach frequently found the pus cocci in healthy eyes. He describes 
twenty-seven different micro-organisms, eighteen of which were micrococci. He says 
that in a large percentage of normal sacs bacteria may be demonstrated and that the 
conjunctiva must be regarded as constantly infected. 
Lawson 9 in a series of two hundred cases found the healthy conjunctival sac 
sterile forty-one times. Serum was used throughout for the primary inoculations. 
In sixteen cases only were pyogenic cocci isolated ; staphylococcus pyogenes albus 
occurred six times ; staphylococcus aureus, once ; staphylococcus citreus, twice ; 
staphylococcus cereus albus, four times ; Fraenkel's pneumococcus, twice. 
Various non-pathogenic organisms occurred, of which staphylococcus 
epidermidis albus was found fourteen times. Inoculation experiments on the cornea 
of rabbits and guinea-pigs were without result. Staphylococcus aureus was not tried. 
He calls attention to the frequency of the so-called xerosis bacillus and the comparative 
infrequency of pyogenic organisms and their non-virulency. The xerosis bacillus was 
found in one hundred and eighteen tubes, ninety in pure culture. 
Randolph 12 made a series of experiments upon the conjunctivae of one hundred 
individuals. In thirteen cases the conjunctival sac was sterile, and out of the eighty- 
seven fertile tubes he observed that eighty-five contained staphylococcus epidermidis 
albus, whilst only two contained a bacillus. The value of these experiments is 
somewhat vitiated by the fact that in all the cases agar-agar was used as the culture 
medium. Xerosis bacillus, Bac. lacunatus (Eyre), and others will only grow readily 
on serum in primary culture. The experiments are of value in that, although a 
correct estimate of the bacteria of the conjunctival sac has not been arrived at, they 
show not only that the sac is rarely sterile but that the organisms generally found 
therein are of feeble pathogenic power. 
