88 BACTERIOLOGY OF THE EYE 



though there are strains which remain permanently bleached, and then appear as a 

 dirty white Staphylococcus pyogenes. 



Bouillon and gelatine, in which the StapJiylococcus pyogenes aureus grows rapidly, 

 become acid, the latter showing a beautiful liquefaction, with the formation of an 

 orange-yellow deposit at the bottom of the excavation. When the gelatine is 

 completely dissolved, and similarly in the bouillon, a thick slimy deposit is formed. 

 The cultures smell like sour paste. The formation of acid is specially strong in the 

 case of media containing sugar. Milk is coagulated. 



Aureus remains living and virulent for a very long time, but its pyogenic 

 properties gradually disappear on cultivation, though they can be regained 

 by passage through an animal. 



Its pyogenic activity in the cornea causes ulceration ; if very virulent, rapid 

 perforation and panophthalmitis. Infection of the anterior chamber and of 

 the vitreous as a rule leads to panophthalmitis and discharge of the pus externally. 

 The degree of inflammation depends, of course, upon the number and the virulence 

 of the organism in question (cf. p. 79 of the ' Researches of Andogski '). Less acute 

 inflammations may occur, just as in the case of ulcerative and fungating endo- 

 carditis. In the serous cavities, and also in the eye, such cases have been observed 

 (cf. 'Wound Infection,' p. 159). These have been experimentally studied by Leber 

 and Deutschmann. 



Among the pyogenic toxines 1 formed by the aureus, the most important are 

 leukocidin (Van der Velde), and staphylolysin, a powerful hsemolytic poison, 2 

 isolated by Neisser and Wechsberg, which is very readily obtained from blood-con- 

 taining media. This hsemolytic action and the power of producing a hsemolytic 

 serum and immunity, according to M. Neisser, is peculiar to the pyogenic forms, 

 and supplies a delicate differentiation from the purely saprophytic Staphylococci. 3 

 An agglutinating serum is produced, and a ' serum diagnosis ' in cases of 

 staphylococcal infection is possible by testing the clumping power. It must 

 be admitted that a positive result is not always feasible in an isolated staphylococcal 

 infection. 



According to the researches of Neufeld and Eimpau, and also of Wright, the 

 ' bacterio -tropic ' property of the serum i.e., the increased phagocytic action 

 is often increased against StapJiylococcus in the case of staphylococcal infections. 

 A positive diagnosis by this means has not yet been made. 



Besides the Staphylococcus pyogenes aureus, there are a number of other cocci 

 which produce a yellow pigment. 



Lehmann and Neumann classify the other cocci which develop sulphur or lemon- 

 coloured pigments on gelatine and agar as follows : Micrococcus luteus (powerfully 

 liquefying ; gelatine culture coarsely granular) ; Micrococcus flavus (Fliigge 

 gelatine culture finely granular, powerfully liquefying) ; and Micrococcus sulphureus 

 (Zimmermann gelatine culture finely granular, not liquefying). All three are 

 non-pathogenic. 



The Micrococcus aurantiacus, found by Basso and Bach on the 

 conjunctiva, and also occurring often in the air, is orange-yellow, does 

 not liquefy gelatine, and is non-pathogenic. 



1 By a process of alcohol precipitation, Leber demonstrated an intensely pyogenic 

 chemiotactic deposit of phlogosin, which contained the staphylococcal poison. 



2 Concerning the further toxic actions necrosis, pigmentation, leucocytosis and 

 fermentation, see Neisser and Sipstein, loc. cit. 



3 Dr. Rupprecht and myself have had results with the Staphylococci found in the eye 

 which contradict this : we found hfemolysis in the case of non-pathogenic strains from the 

 conjunctiva. 



