610 NON-PATHOGENIC MICROCOCCI. 



fied gelatin ; by reflected light the colonies are of a whitish lustre. In gela- 

 tin stick cultures development occurs along the line of puncture, and lique- 

 faction commences on the second day along the entire line, forming a tube 

 of rather uniform dimensions ; the liquefied gelatin is slightly 

 clouded, and a very slight deposit of a white color is seen at 

 j^jjP the bottom of the tube ;. by the eighth to tenth day liquefac- 



MB ^& tioii is complete ; in older cultures a finely granular, whitish 



>* deposit is seen, while the gelatin above is quite transparent 

 ** and has an acid reaction. Upon agar a very scanty super- 

 ^^ f ficial growth occurs. Blood serum is not liquefied, but 

 vW / small, shining scales are developed upon the surface. Upon 



FIG. 201. Str. young potato a thin layer of white, button like colonies de- 

 coli graciiis,from velops upon the surface; no growth occurs on old potato, 

 a liquefied geia- Milk is coagulated and acquires an acid reaction after a con- 

 tin culture, x siderable time. 



970. (Escherich.) 



213. STREPTOCOCCUS ACIDI LACTICI (Grotenf eld) . 



Found in coagulated milk in Finnland. 



Morphology. Spherical or oval cocci, from 0.5 to 1 jj. long and 0.3 to 0.6 

 H thick, associated in long chains. 



Biological Characters. An anaerobic (not strict), non-liquefying strep- 

 tococcus. Grows in the usual culture media at the room temperature. Upon 

 gelatin plates forms spherical, white colonies best when the plate is cov- 

 ered with a layer of gelatin to exclude the air. In gelatin stick cultures an 

 abundant development along the line of puncture only. In milk causes co- 

 agulation of the casein and an acid reaction. 



214. STREPTOCOCCUS GIGANTEUS URETHRA (Lustgarten). 



Found in the normal human urethra. 



Morphology. Spherical cocci, 0.8 to 1 n in diameter, associated in chains 

 which often contain many hundred elements, and are often united in thick, 

 tangled masses. 



Biological Characters. An aerobic micrococcus. Grows slowly in nu- 

 trient agar at 37 C. ; does not grow at the room temperature. Upon agar 

 plates elongated, drop-like colonies are slowly formed, which are not ele- 

 vated above the surface ; these are easily overlooked in reflected light, and 

 in transmitted light are iridescent; the colonies are often shaped like a clover 

 leaf ; they never become confluent, and attain their greatest development by 

 the eighth day ; transplantation to other agar tubes is rarely successful. In 

 streak cultures upon agar development occurs for the most part in the con- 

 densation water as a flocculeiit deposit. 



215. STREPTOCOCCUS ALBUS. 



Synonym. Weisser Streptococcus (Maschek). 



Found in Freiburg water by Tils. 



Morphology. Streptococci, which show independent movements when 

 undergoing binary division (Tils). 



Biological Characters. An aerobic, liquefying streptococcus. Grows 

 in the usual culture media at the room temperature. Upon gelatin plates 

 superficial colonies are developed, which are flat, circular in outline, and 

 bounded by a white margin ; saucer-shaped liquefaction quickly occurs, and 

 under a low power a pale-brown cloud is seen in the centre. Upon agar 

 the disc-shaped colonies have a darker interior. In gelatin stick cultures 

 the development is chiefly upon the surface ; liquefaction progresses rapidly, 

 and a white deposit is formed. Upon potato a slimy, white layer is quickly 

 developed. 



