EEMAEKS ON TECHNIQUE 5 



immunity, both of the organism generally and the particular tissue 

 affected, have also an influence. Each of these circumstances can 

 modify the clinical progress of the disease, and also the inoculation 

 results. We must therefore be very careful on obtaining a negative 

 result not to commit the common error of rashly concluding that the 

 case is not a septic process, but a pure case of ' toxic inflammation ' 

 or a ' toxic metastasis.' 



Inoculations should not generally be made from the interior of the 

 living eye, as the introduction of an instrument is too risky. In deep 

 wound infections, therefore, an etiological diagnosis can only excep- 

 tionally be made intra vitam oculi. Opportunity for inoculation is 

 most usually given when a foreign body is removed ; the foreign body 

 should then be rubbed on agar, or introduced into bouillon. Enu- 

 cleated eyes or exenterated contents, on the other hand, are very often 

 available for examination. 



Tough or compact material (cone rements from the canaliculi, or the 

 contents of follicles, etc.) can be squeezed out with a sterile glass rod, 

 or teased out in saline with sterile needles ; this is absolutely necessary 

 when such material is to be used for direct injection into any test 

 animal. Morax uses a method of treating trachoma follicles by 

 rubbing them down with sand before inoculating them on to the 

 medium. 



Staining 1 Methods. 



The material is spread out on a slide, dried in the air, and 

 then passed three times through a flame to fix it. In the case of 

 bouillon cultures the drying process must be carefully attended to, 

 for when a damp preparation is drawn through the flame the bacteria 

 in it may be very distorted. It is sometimes useful to fix by alcohol 

 or sublimate, in which the air-dried film is laid for about ten minutes ; 

 in the case of sublimate the preparation must be passed through an 

 alcoholic solution of iodine, and then ordinary alcohol before staining. 



When stained the preparation can be examined in water under a 

 cover-glass. Many details are thus shown more clearly than when it 

 is in balsam ; single individuals appear larger, and the features of 

 very small organisms, such as Koch-Weeks and influenza, are more 

 readily seen. Such preparations can again be dried and mounted in 

 balsam. 



For a simple aniline stain Loffler's methylene blue (Loffler's 

 universal method), and dilute carbol fuchsin can be recommended. 



