CERTAIN GENERA OF THE CLOSTRIDIACEAE 29 



proteolytic action of these organisms on meat must have used an 

 acid meat medium, or a substratum poor in peptones and pep- 

 tids, or must have incubated their cultures at room temperature. 

 Von Hibler found that the organism blackened brain medium. 



Genus 25. Metchnikovillus nov. gen. 



Highly proteolytic PiUrificoideae that readilj^ blacken meat. 

 They do not produce in it abundant amino-acid crystals, but 

 digest meat, serum, egg and casein rapidly, forming more alkali 

 or less fatty acid than do the organisms of the succeeding group. 

 They split few sugars. Gram-positive or weakly Gram-positive 

 rods, vegetative forms uniform and considerably smaller than 

 sporangia. Sporulate readily in ordinary media, forming oval 

 spores which are usually sub-terminal, though in some strains 

 median spores predominate. ^Multiplication is exceedingly active, 

 forty-eight hour colonies in deep agar are large and woolly. Fre- 

 quently a few colonies are larger than the others but they do not 

 give rise in a following generation to a preponderating number 

 of large colonies. Ubiquitous. Common intestinal organisms, 

 abundant in soil; very common in infected wounds. Not capable 

 of invading in pure culture in moderate doses, may invade in 

 company with other organisms or alone when given in large doses. 



Type species M. sporogenes {Bacillus sporogenes type A of 

 Metchnikoff) as described by the Committee (p. 36). Klein 

 described as B. enteritidis-sporogenes a mixed culture which 

 contained a non-proteolytic organism, a pure culture of which 

 was described by von Hibler as B. enteritidis-sporogenes Klein 

 (von Hibler IV) . This tissue invading pathogen, thought by some 

 to have been B. Welchii,\^ most nearly referable to the genus Arlo- 

 ingillus. The strain was derived from patients with enteritis and 

 it was apparently contaminated with a proteolytic organism of 

 the genus Metchnikovillus. Metchnikoff described two types, A 

 and B, of intestinal anaerobes which he thought were similar 

 to the organism of Klein, and which he termed B. sporogenes. 

 His descriptions permit of no identifications. Choukevitch, 

 working in ^letchnikoff's laboratorj^ described B. sporogenes 

 A and B more carefully. Type B should be referred to genus 



