2 BACTEK10LOGY OF THE EYE 



when dealing with a single case, and also when an epidemic is being 

 considered. In the latter instance, therefore, those cases should 

 always be examined which have not yet passed the height of the 

 inflammation. 



The discharge should be taken from the conjunctival surface, 

 avoiding contamination as far as possible, and it should be collected 

 before it has come in contact with the angles or margins of the lids. 

 In many instances a pure culture will thus be obtained, and the 

 causal organism alone will be seen in the smears. If, however, any 

 contamination with the lids or skin should occur, the preparation will 

 show a more or less free admixture of skin organisms, especially 

 Staphylococci and Xerosis. When, as often happens, the discharge is 

 so scanty that it cannot be thus obtained from the conjunctiva, 

 we must use that which collects at the inner angle for our preparations. 

 Such is often the case in slight cases of diplobacillary conjunctivitis. 

 The preponderance of the true pathogenic organism over the others 

 will still be quite marked. If we wish to make cultures in such cases, 

 it is better not to use the secretion at the angles, but to pass the loop 

 to and fro in the moist lower fornix; some organisms will thus be 

 collected, generally in sufficient numbers for culture purposes. 



To make a microscope slide a small flocculent mass of the secretion 

 is obtained, as free as possible from tears ; this is then rubbed 

 with the platinum loop on a carefully cleaned slide, so as to form 

 an even, thin layer. It is especially necessary that the layer should 

 be thin and even, for with Gram's staining the same organism may 

 show positive or negative, according to the thickness of the tissue 

 and the varying protection thus afforded it against the decolorizer. 



Under the heading 'Conjunctivitis ' this subject is fully treated. 



2. THE CORNEA. 



To avoid injury to the tissues the greatest care must be exercised in 

 obtaining material from corneal infiltrates or ulcers. The eye must 

 be cocained and kept perfectly still, either by fixation through the lids 

 with the fingers, or by forceps and speculum. 



The secretion is carefully wiped away from the cornea with a sterile 

 swab, and some of it kept for examination. We must not, however, 

 put too much reliance on the examination of this secretion, for 

 the true exciter of a corneal process is frequently not found on the 

 surface, but lies deeply placed in the infiltrated corneal tissue ; for 

 example, in cases of diplobacillary conjunctivitis the cornea may be 

 infected by Pneumococci (Hoffmann, Zur Nedden). This explains why 



