22 BACTERIOLOGY OF THE EYE 



done on the luxated eye of a rabbit), and rubbing into it with a 

 platinum loop some of the material in question. In the latter case 

 so large an amount of the material is introduced into the tissues that 

 the conditions are not parallel to those which obtain when the human 

 eye is infected. 



The inoculation wound must be made very obliquely in fact, almost tangen- 

 tially to avoid perforating the thin cornea. It is advisable always to make a 

 wound of the same size and position, and to use the same amount of material, so that 

 a comparative idea of the virulence may be obtained. The same infecting agent, 

 when centrally placed, will cause a more severe reaction, especially in the iris, than 

 when in the neighbourhood of the vascular limbus. 



With a very fine sharp cannula some infected fluid can be injected 

 into the substance of the cornea. This is a rather more difficult 

 technique, and the greatest care is necessary not to perforate the 

 cornea. 



In all these corneal inoculations in animals it must be borne in 

 mind that large wounds, especially those forming a pocket, can 

 become secondarily infected by other organisms from the conjunctiva 

 or surroundings. 



When an infection has resulted, it should be verified by removing 

 material out of the pocket. I have often found that after an in- 

 oculation with Pneumococcus, this organism did not develop in the 

 resulting purulent keratitis, as it happened to be of low virulence for 

 the animal, but that Staph. pyogenes aureus was very plentiful. 



An inoculation of the anterior chamber with solid or viscous 

 material is easily made on the cocainized (not luxated) eye. After 

 puncture more cocaine is instilled, and then a small particle is pushed 

 in with an iris forceps or stylet. After a little practice this can be 

 done without assistance. The puncture is best made up and out, as 

 here the nictitating membrane is not in the way. The particle must 

 be placed on the iris far enough from the wound, so that it will not be 

 again extruded. The iris should be replaced out of the wound as 

 thoroughly as possible. 



When the material cannot be pushed in solid, it must be teased out in sterile 

 fluid, and (as hi the case of bouillon cultures, bacteria emulsions, pus, etc.), injected 

 with a syringe. The aqueous should be first allowed to run out, as otherwise the 

 injection could only be made against a rising tension, and when the syringe is 

 removed the fluid would be squeezed out again. 



For vitreous inoculations very small amounts can be at once 

 injected through an oblique puncture. Larger amounts will cause an 

 increase in tension, and when they must be used the anterior chamber 



