330 TEXT-BOOK OF BACTERIOLOGY 



XXV. BACILLUS PYOCYANEUS p (ERNST). 



Ernst has described a special variety of the bac. pyocyaneus 

 (called by him Bac. pyoc. /5) producing, as he states, a blue pig- 

 ment, the blue pus, while the other variety exhibits the green fluo- 

 rescent pigment. Both are said to appear often in common under 

 natural conditions, and to develop a mixed hue intermediate be- 

 tween the colors just mentioned. 



XXVI. GONOCOCCUS. 



Gonorrhoea is a disease principally distinguished by the copious 

 secretion of pus. Everybody knows, and daily observation con- 

 firms, that this pus differs very clearly from the products of 

 other processes of inflammation by peculiar contagious properties. 

 There are, in fact, but few affections so strongly marked as being 

 of infectious origin, for which reason efforts have long been made 

 to discover the micro-organism causing gonorrhoea. 



Neisser, in 1879, called attention to the circumstance that pecu- 

 liar cocci are regularly found in this pus, differing from similar bac- 

 teria by their appearance and shape. Their occurrence proved to 

 be exclusively restricted to gonorrhoea, and Neisser did not hesi- 

 tate to declare them to be the cause of a specific inflammation of 

 the urethra, and called them gonococci. 



They are large micrococci, almost always appearing as diplo- 

 cocci. Their areas of contact are usually strongly flattened so that 

 each pair looks like a breakfast " roll/' There is frequently seen, 

 as a sign of commencing division in single members, a shallow fur- 

 rowing, destined to separate the body of the coccus into halves 

 which are not always quite equal. Groups have not been observed 

 unless we designate as such the dense heaps in which the gonococci 

 usually aggregate. 



The cocci prove accessible to the common anilin colors and fur- 

 nish very plain pictures with methyl-blue. Gram's method is not 

 applicable, the bacteria again decoloring when coming in contact 

 with iodide of potassium. An excellent method of preparing them 

 consists in treating the cover- glasses for a few minutes with a 

 concentrated alcoholic solution of eosin (by heating the staining 

 fluid), in absorbing the surplus of eosin by blotting paper, and at 

 once allowing concentrated alcoholic methyl-blue to act (for fifteen 

 seconds at most), and then washing it with water. The cocci will 

 then be seen stained blue on a red ground ; the cellular elements of 

 the blood or pus have eagerly absorbed the eosin, while the nuclei 



