296 IMPORTANT VARIETIES OF FISSION-FUNGI. 



albuminous nutrient media. It grows at quite low tem- 

 peratures (ice-box) and in the incubator. According to 

 Levy and Meyerhof, gas production is most abundant 

 when oxygen is freely admitted, as when the bacteria are 

 grown in shallow dishes. 



Gelatin Plate. 1 — (a) Natural size: Gray, delicate, trans- 

 parent growths which present a shallow depression even 

 after twelve to twenty hours. After three days the cups 

 of liquefaction are already 0.5 to 1 cm. wide, with turbid 

 contents. The deep colonies are punctiform and not char- 

 acteristic. Before liquefaction there is usually seen about 

 the superficial colonies an irregularly jagged zone, consist- 

 ing of highly refractive zoogleae (31, v). 



(b) Magnified sixty times: Upon very young plates two 

 kinds of colonies are seen — the one, roundish, grayish- 

 yellow, sharply outlined, with even borders, homogeneous 

 or finely granular, which lies deep in the gelatin ; the 

 other, transparent, colorless, delicate, wdth wavy lobu- 

 lations, difficult to distinguish from those of Bact. typhi, 

 which lie upon the surface. The latter spread out more 

 and more, and then there appears in the center of the 

 colony a lively, interesting motion of the bacterial masses. 

 After a longer time the motion ceases, while liquefaction 

 extends at the periphery. The colony then is of an irreg- 

 ular form, and when the entire colony is almost completely 

 liquefied, the thin shining peripheral portion remains. 

 The deep colonies often present hairs, which later are 

 mostly arranged about the periphery. 2 



Gelatin Stab. — Stab: At first is thread-like and not 



1 Sugar gelatin is not liquefied, the growth upon this medium being 

 entirely similar to that of the Bact. Zopfii, but in the stab the out- 

 growths are absent (Kuhn). 



2 The representation given is taken from a culture which has been 

 long cultivated and often studied. Not rarely, especially in freshly 

 isolated cultures, one observes on gelatin plate cultures sausage-shaped, 

 spiral zoogleae exactly identical with those which we have described 

 and illustrated so minutely in the Bacterium Zopfii, and which Hauser 

 has so beautifully photographed. Schedtler (C. B. n, 437) appears to 

 have submitted cultures similar to those represented by us. We have 

 sometimes noticed the swarming islands at the periphery of the colo- 

 nies, which, according to Hauser, are especially observed upon 5% 

 gelatin. 



