THE NOEMAL CONJUNCTIVA 27 



Blagoweschenski wiped the conjunctiva with a sterile sponge, which was then 

 ground up and inoculated on tubes. Dubief in the same manner used wool swabs. 

 This method guaranteed a thorough inoculation, but more easily allowed a con- 

 tamination, and may have been the explanation of his finding in thirty-four 

 individuals the uncommonly large number of eighteen different bacilli : ten Cocci, 

 five Tetrads and Sarcince, and one Streptococcus. 



8. Variations in the media and the technique employed are to a much 

 greater degree responsible for the tremendous variations in the results of 

 fanner years. 



The media are of slight importance in the case of the Staphylococci, 

 and the similar vigorously growing organisms, which here, as well as 

 in other parts of the body, attracted attention in the early days of 

 bacteriology. Eegarding them, the findings from the first have not 

 varied much, when we consider the actual variations which are 

 possible. 



A very different state of affairs occurs in the case of B. xerosis. This 

 has often only a very slight power of growth, due to the scanty nutrition 

 which the tear- washed conjunctival sac affords. On its most sus- 

 ceptible media, therefore (blood-serum or ascites agar), after twenty- 

 four hours, only scanty weak colonies can be seen ; ordinary agar often 

 enough shows absolutely nothing. If we leave the test culture for 

 several days in the incubator, colonies may sometimes appear at places 

 which at first were bare. I have often been astonished to find how 

 apparently sterile cultures have developed numerous colonies of 

 Bacillus xerosis after eight days or more in the incubator. 



Other organisms again, like Pneumococci and Diplobacilli, depend 

 upon the alkalinity of the medium for their growth. 



Media which contain haemoglobin must be used to decide the 

 important question to what extent bacteria of the influenza group are 

 normally present. Giarre", Picchi, and Eymowicz have used this 

 means of examining the normal conjunctiva. Further research in 

 this direction appears desirable. 



With regard to the methods of examination, it must here be noted 

 that single colonies of Pneumococci and also influenza bacilli can often 

 only be discovered after most careful examination with a loop. Such 

 colonies of Pneumococci, especially when on moist media, very rapidly 

 become invisible by their margins merging with the surface moisture ; 

 besides which, when they are taken from the normal conjunctiva a 

 very unfavourable nidus for them they have a very short life, and 

 degenerate rapidly. 



In the great majority of the older articles concerning the flora of 

 the normal conjunctiva insufficient attention is paid to these par- 



