BACTERIUM DISCIFOBMANS. 263 



(a) Upon gelatin a soft white growth, uninfluenced by cane-sugar, 

 (a) The mucilaginous material secreted remains unstained with 



iodiu. Bacterium rancens ' Beijerinck. 

 (/3) The secreted slime is turned blue by iodin. Bacterium 

 Pasteurianum Hansen. 

 (J) Upon gelatin, dry, tough, leathery mass ; upon beer, there is 

 at iirst a slimy and then a thick, leathery scum, which gives the reac- 

 tion for cellulose. Cane-sugar influences the luxviriance of the growth. 

 Bacterium xylinum Brown. 



How this classification will stand the test of more exact 

 morphologic investigation remains undecided. In the 

 mean time the Bact. xylinum should be considered as 

 a leukonostoc — i. e., it then belongs to the streptococci. 

 Of the other varieties, which are represented as non- 

 motile rods, usually motile forms are also observed. The 

 work of Hoyer is very rich in biologic detail regarding 

 the nutrition of those which produce acetic acid, etc. 



Bacterium disciformans. Zopf. 



Synonyms. — Bacillus disciformans Zimm. (ii, p. 48), 

 Bacillus azureus Zimm. (ii, p. 24). 



Short rods (0.3-1.4 /i long, 0.3-0.5 fi thick), non-motile, not stained 

 by Gram's method, grows also as an anaerobe. Upon the gelatin plate : 

 Very young deep colonies, rather coarsely punctate, round, trans- 

 parent ; superficial colonies, partly like typical young typhoid cultures 

 (especially in the B. azureus), partly somewhat more compact, re- 

 sembling more tlie colon type. The superficial colonies liquefy after 

 the second day, when there is frequently seen a narrow hair-like 

 zone. The ma.ss lying on the bottom of the plate is a little denser in 

 the disciformans than in the azureus, and with both there are open 

 spaces. The deep colonies later present little tubercles, and, when 

 they come to the surface, liquefaction and a hair-like rim. In gelatin 

 stab : Funnel- to tube-shaped liquefaction, developing rather rapidly. 

 Bouillon ; very cloudy, abundant H^S and a little indol produced. 

 Upon agar : Dirty white, slimy, luxuriant growth. The agar is col- 

 ered brownish to rosy red. Upon potato : Grayish-yellow to reddish- 

 brown, moderately elevated, moist growth. Grape-sugar is fermented, 

 with abundant formation of gas. Milk is first coagulated, then again 

 rendered fluid. 



1 "We found the Bact. rancens not growing very rapidly and some- 

 what elevated upon solid nutrient media with an oily gloss. No 

 liquefaction of gelatin, no anaerobic growth. Grape-sugar Is fer- 

 mented, with formation of gas and acid. 



