302 THE STREPTOCOCCUS-PNEUMOCOCCUS GROUP 
tiiral methods, isolated streptococci from a case of erysipelas; Rosen- 
bach^ studied the organism in great detail and introduced the name, 
Streptococcus pyogenes. 
Morphology. —The individual cells are spherical, less commonly 
oval, measuring from 0.5 to 1 micron in diameter. The size of indi- 
vidual cells varies somewhat even in the same culture. The organ- 
isms remain adherent in chains which vary in length from four to 
twenty or more elements, in which a definite association of cocci in 
pairs with their proximate sides flattened is occasionally observed. 
The number of elements in the chain varies somewhat according to 
the origin of the culture; it has been observed that streptococci freshly 
isolated from lesions tend to occur in longer chains, while those organ- 
isms which grow" habitually upon the normal surfaces and mucous 
membranes of the body appear more frequently in shorter chains, 
V. Lingelsheim^ has designated those strains which form chains of 
eight or more cocci, Streptococcus longus; the short-chain types are 
called Streptococcus brevis. Notwithstanding the frequent parallelism 
of pathogenesis and development of long chains of cocci in artificial 
media, in contradistinction to the lesser virulence of the short-chain 
types, experience has shown that the length of the chains may also be 
influenced directly by variations in the culture media.^ This dis- 
tinction, therefore, would seem to be untenable. Cowman* on the con- 
trary, has shown that the typical translucent colonies may give rise to 
short chains of streptococci which suspend uniformly in broth, while the 
variant which has a thicker, more dense colony, gi\'es rise to longer 
chains, but sediments out rapidly in broth. The former is more viru- 
lent. Streptococci grown on solid media are prone to group themselves 
in pairs, or even irregular masses, resembling staphylococci. Similarly, 
the typical streptococcal arrangement is frequently lacking in purulent 
inflammations of streptococcal causation. Occasional cells in a chain of 
streptococci, especially in old cultures, are met with which are distinctly 
larger than their fellows; they color somewhat differently and were 
formerly regarded as spores— arthrospores.^ It is now known that 
they are not noticeably more resistant than the more typical cells, 
and they are probably to be regarded as in\'olution forms. 
Streptococcus pyogenes is non-motile, non-flagellated, and does 
not produce true endospores. Occasional strains, isolated directly 
from lesions or from animals, exliibit a delicate stainable zone around 
individual organisms or pairs of organisms, which suggests capsules. 
Howard and Perkins*' have isolated such an organism which exhibited 
a very definite capsule. It grew habitually in short chains in fluid 
1 Mikroorganismen bei Wundinfektions-krankh. des Menschen, Wiesbaden, 1884. 
2 Ztschr. f. Hyg., 1891, 10, .331. 
' See Aronsoa (Berl. klin. Wchnschr., 1896, 33, 717; 1902, 39, 979) and Vincent 
(Arch, de med. exp., etc., 1902) for details. 
4 British Jour. Exper. Pathol., 1922, 3, 187; 1924, 4, 241. 
5 Hueppe: Die Methoden der Bakterien-Forschung, Wiesbaden, 1889, pp. 24, 130. 
« Jour. Med. Res., 1901,6, 163. Holman: Jour. Pathol, and Bactcriol., 1915, 19, 478. 
