188 BACTERIOLOGY OF THE EYE 



inulin-water (1 part 1 per cent, inulin-serum and 3 parts water) only 

 occurs with Pneumococci ; there are, however, Diplococci without cap- 

 sules, with a tendency to the formation of chains, which can ferment 

 inulin. 



Many agree with Schottmiiller that growth on blood - agar is 

 decisive. On this medium the pneumococcal colonies are surrounded 

 by a greenish area, while around Streptococcus pyogenes a clear area 

 (haemolysis) occurs. 



In ophthalmic practice we generally examine a smear preparation, 

 and the difficulties which we have mentioned rarely come into the 

 question, unless, perchance, we have to deal with a mixture of Strepto- 

 coccus and Pneumococcus. 



The agglutination test does not furnish a specific differentiation 

 between Pneumococci and Streptococci, for the individual strains of 

 Pneumococci present considerable differences in this respect, and by 

 no means always agglutinate each other. Frankel and Kindborg 1 

 state that agglutination is only specific for the particular strain 

 from which the serum has been derived. Although K. Scholtz did 

 not find a very rigid specific difference for Pneumococci from ulcera 

 serpentia, still he did find strains which either failed to agglutinate 

 others or did so only very slightly. Experiments with active and 

 passive immunity show similar results. 



The virulence of Pneumococci is very inconstant 2 (vide supra). In 

 cultures obtained from the eye it is, on the average, less than in those 

 from sputum, and even in the first generation a fatal inoculation 

 cannot be made on rabbits. The infected condensed water of a fresh 

 culture (naturally a pure culture) appears to have the highest viru- 

 lence. By passage through a mouse most strains can be exalted, 

 though by this means they lose their pathogenicity for man (an 

 important consideration in the preparation of sera). 



Cultures of high virulence inoculated into rabbits and mice pro- 

 duce a rapid septicaemia, even when inoculated into the eye. Less 

 virulent strains produce local suppuration. A typical ulcus serpens, by 

 the inoculation of a corneal pocket, could only be produced in apes 

 (Eomer), not in any other animal. 



LITEEATUEE. 3 



ABLER- WEICHSELBAUM, Das osterreichische Sanitatswesen, 1897, Nr. 20. 

 VON AMMON, Munch, med. Wochenschr., 1900, Bd. 1, S. 12. 



1 Inaug. Diss., Halle, 1905. and Zeit. f. Hyy. u. Inf. 



2 Romer, Rep. Heidel. Conf., 1907. 



3 Cf. the general literature on 'Conjunctivitis,' p. 118. 



