220 BACTEKIOLOGY OF THE EYE 



slimy deposit, which was homogeneous when shaken up. At 18 C. there was only 

 a slight growth in the upper part of a stab in gelatine. Milk was not coagulated. 

 They fermented all sugars except mannite and galactose. They were not influenced 

 at all by meningococcal serum. 



Brons is in doubt whether the varieties may not approach each other still more 

 on further cultivation. 



The Abelsdorf-Neumann Diplococci are so far peculiar in comparison with the 

 typical catarrhalis, in that they form milk-white colonies on agar ; they also 

 slowly liquefy gelatine. 



Differential Diagnosis of the Gram-Negative Diplococci 

 found on the Conjunctiva. 



From what has already been said, it is obvious that the Gram- 

 negative Diplococci can present such difficulties in their differential 

 diagnosis that in some cases it is only possible after cultures have 

 been made, and in the cases of Gonococci and Meningococci after 

 agglutination tests have been carried out. This certainly is fre- 

 quently seen, but still in a great many cases differentiation is possible 

 without these special means. Anyone who is moderately familiar 

 with the appearance of the Micrococcus catarrhalis will recognize it 

 often in smear preparations, on account of its difference in size and 

 shape from the Gonococcus, the small amount of secretion present 

 in proportion to the numbers of the cocci, and the free admixture 

 of other organisms (Staphylococci, xerose bacilli, etc.) ; the secretion 

 is also very poor in cellular elements. The very appearance of the 

 slide conveys the idea of a saprophytic growth, as Brons has 

 pointed out. A plate in the K. M.f. A., 1907, Bd. i., shows this very 

 well. The admixture of other Bacteria is not quite so obvious in 

 Plate III. of the present work, as only a small field is there repre- 

 sented. The question between these organisms is easily settled by 

 cultures (vide supra). The Meningococci present much greater diffi- 

 culties in their differential diagnosis. 



Under certain circumstances agglutination tests are necessary. 

 The test by inoculating the urethra cannot be applied. With that 

 test the differentiation is very easy, as numerous inoculations of 

 Gonococci on the human urethra always caused a blennorrhcea ; while 

 similar inoculations which Zupink made with fresh cultures of 

 Meningococci in the same situation were always negative. This is 

 a biological proof that the Gonococcus, in spite of morphological and 

 cultural similarities, is not identical with the Mcningococcus. Such a 

 method of determination, however, is not available for us. 



It would be quite incorrect to conclude that the slide diagnosis 

 of the Gonococcus is of no use. It has only lost, relatively, some of 



