STREPTOCOCCI 233 



Morphology. The streptococci are non-motile cocci, 

 each cell measuring about 1 JUL in diameter. They stain 

 well with anilin dyes and are Gram-positive. 



Fission takes place in one direction only, so that chains 

 of cocci are formed. A cell here and there in a chain is 

 often somewhat larger than its fellows, and some authors 

 have considered these enlarged individuals to be arthro- 

 spores. 



The length of the chains is very variable and may be 

 modified by cultivation, and occasionally branch- chains 

 form. 



Von Lingelsheim distinguished two varieties, brevis and 

 longus, the former rendering broth turbid, growing in 

 short chains, and being non-pathogenic to mice and 

 rabbits, the latter leaving the broth clear, growing in long 

 chains, and always pathogenic to these animals. 



Gordon 1 divided the streptococci into four varieties, viz. 

 (1) the S. longus, isolated from the mouth, restricted to 

 an organism forming exceptionally long chains ; (2) S. 

 medius, including the majority of streptococci from pus, 

 sepsis, and erysipelas, and Lingelsheim's longus ; (3) S. 

 brevis, including Lingelsheim's brevis and the Diplococcus 

 pneumonia ; (4) S. scarlatince or conglomerate, isolated 

 from scarlatinal angina. 



Cultural reactions. The streptococci can be cultivated 

 on the ordinary culture media, and usually grow both 

 aerobically and anaerobically. On agar, or better, glycerin 

 agar, minute whitish, semi-transparent, more or less 

 isolated colonies form in twenty-four to forty-eight 

 hours (Plate II. c). On gelatin the growth has much the 

 same characters, and is better seen, as this medium is 

 clearer than agar, but it takes some days to attain the 

 maximum. In stab-cultures minute spherical colonies 

 develop all down the line of the stab, but without invading 

 1 Rep. Med. Off. Loc. Gov. Board for 1898-99, p. 482. 



