324 BACTEKIOLOGY OF THE EYE 



marginal infiltrates and ulcers, on the other hand, the bacilli are 

 scanty, so that in the smear preparation single examples are only seen 

 with difficulty. In the bacteriological examination of marginal ulcers 

 cultures are essential if the Zur Nedden bacillus is to be sought for. 



Prolonged culture has not succeeded in making the bacillus 

 approximate any further to any other bacteria. The statement by 

 Lehmann and Neumann that the bacillus belongs to the group of 

 Friedlander's bacillus cannot be confirmed. 



Phlyctenules commonly occur at the limbus. There is no true 

 conjunctivitis. Zur Nedden therefore considers that the infiltrates 

 and ulcers were primary corneal affections, and that they were not 

 catarrhal ; they were also almost always unilateral. Any irritation of 

 the conjunctiva was secondary. In the seqretion of such cases the 

 bacillus could be demonstrated by cultures. 



The ulcers did not usually progress ; hypopyon was rare, but 

 relapses were not uncommon. The disease was more common in the 

 winter. 



Zur Nedden found the bacilli along with Pneumococci in a case of 

 ulcus serpens, and also in a case of neuroparalytic keratitis. 



He never found it in any other circumstances, in spite of numerous 

 examinations of conjunctival and lacrymal affections. 



Inoculations. If an agar culture be diluted with water and a 

 trace of the fluid injected into the cornea of a rabbit, a keratitis of 

 varying severity is produced. In many cases it takes on the form of 

 a hypopyon-keratitis, and may lead to a perforation ; l in others it 

 remains as a benign infiltrate. Cultures which are older, and have 

 been repeatedly subcultivated, have a much weaker action. The 

 bacilli remain for a long time in such corneal infiltrates, and can be 

 again grown in a pure condition. When, however, they are injected 

 into the interior of the eye, the vitreous, or anterior chamber, they 

 cause a transient reaction of varying severity in the connective 

 tissues, and within twenty-four hours they die out. This result is 

 due to the need of oxygen. Inoculations on other animals, and in 

 other parts of the body, produce no reaction. The Zur Nedden bacillus 

 is therefore a bacillus which is only pathogenic in the eye, and one 

 too, which has a stronger action in the cornea than in the vitreous. 



It is only in exceptional cases that an injury has preceded the 

 ulceratiori ; the bacillus must therefore have the power of attacking the 

 uninjured cornea from the conjunctiva. This it does in the marginal 



1 A purulent destruction of the cornea, due to a pure infection with this bacillus, has 

 never been observed in man. The formation of a hypopyon even is rare. 



