336 BACTERIOLOGY OF THE EYE 



For the production of aggressin, it is not essential, as Bail thought, to have an 

 exudation that is produced by living tissues ; it can be obtained directly from the 

 bacteria themselves. 1 It therefore seems very doubtful whether in this aggressin 

 treatment we obtain any results essentially different from those obtained by the 

 ' active ' method of immunizing ; probably the preliminary solution of the bacilli 

 frees the aggressive substance or endotoxin before the injection, so that the body 

 will react immediately and perhaps more strongly, while in the other case after the 

 injection the first solution of the bacteria must occur in the body. Accepting Wasser- 

 mann's point of view, and provided that an aggressin method for Pneumococci of 

 practical utility can be evolved, we may anticipate that the action may be perhaps 

 gradually increased, though it does not present any features different from the 

 methods already in use. 



Amongst the pneumococcal infections of the eye with which we have to deal, we 

 can leave pneumococcal conjunctivitis out of the question of serum treatment, as it 

 is a benign affection which generally heals by crisis, and is amenable to the usual 

 treatment for conjunctivitis. At the very most it can only come into question in 

 the exceptionally severe cases. 



The same is true for the very common pneumococcal dacryocystitis. In cases 

 where it cannot be cured by probing, etc. that is, in old and severe cases, 

 especially in the working classes, where for social reasons such a treatment 

 cannot be carried out the sac can be extirpated, and thus the disease radically 

 removed. 



The rarer pneumococcal infections of the orbit and metastatic pneumococcal 

 ophthalmia are only very rarely available for serum treatment. 



As we have already said, pneumococcal infections of the cornea are 

 of the greatest importance. 



Seeing that, as Romer has shown in his work, 2 the ulcus 

 serpens itself, on account of the feeble absorptive powers of the 

 cornea, does not form any appreciable quantity of specific antibodies 

 in the blood, the body requires a therapeutical increase of its resisting 

 power. To achieve this, Romer first recommended a passive immuni- 

 zation with polyvalent serum. He was able to prove that such was 

 not without action even in the avascular cornea, and demonstrated 

 that an infection of the cornea of an immunized rabbit with a small 

 dose of virulent Pneumococci had no result, though in a control animal 

 it produced a suppuration. An application of the serum six to ten 

 hours after the corneal infection had a definite action, the process 

 being rendered milder. 



1 This is similar in many respects to the attempts with bacterial extracts referred to 

 previously. Pneumococcal extracts have been previously utilized which, besides living 

 bacteria, also contain their aggressins. The results were unconvincing. 



2 It should be noted that Gatti (Ann. di Ottal., 1902, xxxi., p. 3) worked in the same direc- 

 tion, but obtained negative results. He stated that in animals the eye took no part in the 

 pneumococcal immunity. This was so i'ar correct in that the aqueous contained practically 

 no bactericidal substances ; but in the cornea, with which Gatti did not experiment, the 

 conditions were different. 



