134 IMPORTANT VARIETIES OF FISSION-FUNGI. 



as also in the animal body, very often no chains occur. It 

 is therefore always desirable to prepare bouillon cultures of 

 any variety in which there is a suspicion of a streptococcus be- 

 fore arriving at any conclusion. It is not unusual to find 

 single members in a streptococcus chain of somewhat 

 larger dimensions than the rest, but otherwise exactly re- 

 sembling the other members of the chain. It is, at least, 

 so far not certain that the cells contain arthrospores, as 

 many authors believe. 



Key to the Recognition of the Most Important 

 Varieties of Streptococci. 



I. strings of cocci upon all nutrient media (also upon those con- 

 taining grape- and cane-sugar), without thick capsules; at most, ■with 

 delicate capsules. 



(A) Do not grow as a yellow "creamy layer" upon sheep- and 

 calf-serum, and microscopically are without wide capsules. 



(a) Cocci spherical or, when dividing, hemispherical, capsules al- 

 most always absent. 



1. Gelatin liquefied slowly or not at all. Cells 0.6 fi to 1 /i; long 

 or short chains ; often thrive better anaerobically ; slight growth 

 on all nutrient media ; pathogenic or non-pathogenic. Strept. 

 pyogenes Rosenbach, ' page 135. 



2. Gelatin rapidly liquefied in tube form; cells very minute (0.2 ," 

 to 0.4 /i) ; forms long chains, and grows poorly upon potato, 

 agar, and serum. According to Escherich ( ' ' Die Darmbak- 

 terien des Sauglings, " Stuttgart, 1886, p. 77), it is constantly 

 present in the feces of carnivora. Not pathogenic for guinear 

 pigs. Strept. coli gracUis Escherich. Strept. gracilis 

 (Escherich) Lehm. and Neum. 



(/3) Cocci more or less lance-shaped, capsules usually absent in arti- 

 ficial media, but never in animal body. Upon gelatin, poor growth 

 and no liquefaction. Strept. lanceolatus Gamaleia,^ page 143. 



(B) Form a yellow creamy layer upon fluid sheep- and calf-serum. 

 Microscopically from these nutrient media they have wide unstained 

 capsules. Strept. involutus Kurth, page 149. 



II. Chains of cocci upon grape- and cane-sugar nutrient media with 

 thick gelatinous capsules, which may be ten times as thick on all sides 

 as the chain of cocci. Upon other nutrient media it is not diSer- 



' The streptococci scorn every exact method of division. That 

 given here, while apparently a convenient and accurate scheme of 

 division, suffers very much in the closer description of varieties from 

 peculiarities, transition forms, etc. 



2 Compare also Strept. intracellularis (Weichselbaum) Lehm. and 

 Neum., page 148. 



