Cardiobacterium hominis is a microbial species which, because of its small coccobacillary morphology and selected bacterial properties, was originally thought to be a Pasieure//a-like microorganism. The most striking cultural characteristic observed with E. corrodens is the formation of a greyish, dry, flat, radially spreading colony with an irregular periphery and a moist central core. There are several species of Gram-negative, somewhat fastidious bacillary organisms reposing in taxonomic limbo awaiting the placement with existing or new genera. Microscopically, the organism is Gram-negative, nonacid-fast, nonmotile, and does not form spores. As originally described, the freshly isolated haemophilic bacillus is mainly coccobacillary with a few short rods and dumbbell forms arranged singly and in irregular clumps. The designation group M-1 was applied to saccharolytic microorganisms which produce corroding colonies on blood agar surrounded by a zone of ß-hemolysis.