THE PATHOGENIC HIGHER BACTERIA 611 
resemble those of actinomycosis.^ Wright- has clearly shown that 
true actinomycotic infections are characterized not only by suppura- 
tive processes and granulation tissue formation, but that the pus 
from these lesions contains the characteristic granules or "driisen," 
which are composed of branched filamentous organisms densely packed 
together, with characteristic club-shaped bodies radially arranged 
at the periphery of the colony. The pus from so-called pseudo- 
tuberculosis, streptothrix and cladothrix infections do not exhibit 
these characteristic "driisen." 
Morphology.— Actinomyces bovis is a pleomorphic organism belong- 
ing to that group of microorganisms intermediate between the true 
bacteria (Schizomycetes) and the molds (Hypomycetes) known as 
the Trichomycetes. It is best observed in pus from active lesions, 
in which it occurs in gray or yellowish colonies or granules (driisen), 
frequently large enough to be visible to the naked eye. The colonies 
Fig. 87. — Actinomyces, bouillon culture. 
vary in size but usually measure from 0.5 to 2 mm. in diameter. 
Such a colony, crushed between two slides or a slide and cover glass, 
appears as a rosette-shaped aggregation of densely packed filaments 
which exhibit a radial arrangement. The center is so crowded with 
organisms that it appears opaque and usually contains many ovoid 
bodies measuring from 1 to 1.5 microns in diameter. According to 
Wright'' these ovoid or coccoid bodies are formed by the disintegration 
of the filaments. The periphery of the colony contains many inter- 
laced branching filaments, many of which exhibit on their distal ends, 
an enlargement or "club" which is a hyaline layer or sheath about 
the extremity of a filament. These filaments measure about 10 to 
12 microns in length and the clubs 20 to 30 microns in length by 8 
to 10 microns in diameter. Grown in artificial media, club formation 
' See Foulerton (Trans. Path. Soc, London, 1902, 53, Pt 1, 56) and Neukirch (Ueber 
Strahlenpilze, Strassburg, 1902) for literature. 
2 Jour. Med. Research, 1905, 13, 349. ' Ibid., vol. 13. 
