306 BACTERIOLOGY OF THE EYE 



Pneumococcus is the most common organism in contact with the injured cornea 

 for in the first place Uhthoff and Axenfeld have shown, and Romer has confirmed, 

 that in those cases in which other pyogenic organisms were present along with the 

 Pneumococci in the pus from the sac, the Pneumococcns alone was constantly present 

 in the ulcer a proof that either the Pneumococcus has a peculiar affinity for the 

 cornea, or that in a mixed infection it will completely overgrow the other organisms 

 present. It has also been established that in those cases which do not contain the 

 Pneumococcus, but in which other organisms (Staphylococcus, Streptococcus, 

 Bacillus pyogenes foetidus (Uhthoff - Axenfeld), Bacillus pyocyaneus, ozsena 

 bacillus, Bacterium coli, influenza bacillus (Doetsch and Zur Nedden), have been 

 found, the appearances were not those of ulcus serpens, but of an atypical hypopyon- 

 keratitis, even though the determining cause of the infection (the small superficial 

 wound) was the same. Such records appear in the works of the authors 

 above quoted, and also in those of Kalt, Morax, Coppez, Zirm, Hori, Schim- 

 melpfennig, in such numbers that there can be no doubt that the other pus- 

 producers with the exception of the Diplobacillus only in exceptional cases 

 produce a serpent ulcer typical in every respect. 1 Zur Nedden's results prove that 

 such exceptional cases do occur ; he found a pathogenic Subtilis in two cases of 

 ulcus serpens, and from another he cultivated the Streptococcus. Kruger and 

 Hanke in single cases found a bacillus like a proteus ; Bach and Neumann found 

 short rods, which were not fully identified. 



It is no idle question to ask why, when they settle down in a super- 

 ficial wound, Pneumococci have a tendency to this superficial spread, 

 and that, too, in one direction ; whilst at the same time the part first 

 affected is so rapidly cast off with the formation of fresh epithelium, 

 that the healing process is at work close behind the necrotic spread. 

 Uhthoff and Axenfeld have shown that the Pneumococcus in the tissues 

 of the cornea, just as in culture, rapidly loses its virulence when accu- 

 mulated into dense masses. The organisms are then cast off, and cannot 

 penetrate into the deeper layers of the lamellae, though they are still able 

 to find their way in the horizontally arranged lymph spaces. Romer 

 does not put this influence completely aside, but he considers that the 

 changes in the affected tissue are due rather to the fact that they have 

 become more susceptible to the fermentative action of the leucocytes, 

 and can be thus cast off. The details of how this occurs cannot be 

 determined in every case. 



Uhthoff and Axenfeld have shown that the Pneumococci are most 

 thickly intermingled with leucocytes at the progressive border. 

 Enormous numbers of phagocytes are often found here. This is 

 clearly seen in Fig. 66, and is taken by Doetsch to be the explanation 



1 On closer examination I find that two of Gourfein's three cases did not exactly 

 correspond to what we call Ulcus cornece serpens, in that the base of the ulcer was purulent, 

 and the superficial spread was not very definite. In the cultures from one of the cases 

 Diplococci were found growing in chains, but not pathogenic in animals ; this is often the 

 case with Pneumococci. Gourfein does not say whether the secretion was taken from the 

 margin, a precaution necessary in determining the organisms present ; he only speaks of 

 ' Secretion prise sur 1'ulcere.' 



