226 BACTERIOLOGY 



track. On agar, a stripe-like grey deposit develops rapidly 

 at 35° C. 



Diplococcus albicans tardus. — Unna and Tommasoli found 

 this microbe in cases of eczema. The diplococei are im- 

 motile, sometimes arranged in clumps and chains, and do 

 not liquefy gelatine. Eoundish colonies form on plate- 

 cultures, presenting an uneven lumpy surface when 

 examined under the microscope. The colonies gradually 

 become greyish-yellow, lighter in the centre and at the- 

 margin, so that they appear girdled by a light zone. 

 Thrust-cultures show a superficial yellow coating, surface- 

 cultures on agar a greyish-yellow stripe with uneven edges. 

 Diplococcus citreus liquefaciens. — In cases of eczema Unna 

 and Tommasoli also found immotile cocci which liquefy 

 gelatine by their growth. Whitish dots develop on the 

 plate, which rapidly become fluid and assume a lemon- 

 yellow colour. Thrust-cultures show a yellowish coating 

 at first, but after a few weeks a portion of the lemon- 

 yellow culture is seen floating in the liquefied mass, while 

 the rest, which has also a yellow tint, is found at the- 

 bottom. The lemon-yellow colour on the surface of the 

 fluid mass is particularly characteristic. A yellowish layer 

 forms upon agar, and also on potato. 



Diplococcus flavus liquefaciens tardus. — Besides the micro- 

 organisms just described, the same observers found in cases 

 of eczema diplococei shaped like a roll of bread, which liquefy 

 the gelatine rather slowly. Punctiform brownish-yellow 

 colonies form on the plates, and yellowish masses float on 

 the surface of the gelatine when it has become fluid. In 

 thrust-cultures also liquefaction progresses, but with such 

 extreme slowness that two months elapse before half a 

 cubic centimeter of gelatine is liquefied. A thick slimy 

 coat of greenish-yellow colour develops on agar, and a 

 lumpy sulphur-yellow deposit upon potato. 



