EXPERIMENT STATION BULLETINS. 537 



So well defined were the flavor and odor of germ B that even with the use of 

 a 45 per cent starter of germ A a mere trace of germ B could still be recognized. 

 In our experience germ B could scarcely be detected by isolation after the 

 acidity of the culture reached fifty degrees. This work has considerable practical 

 significance in the use of starters and has some value scientifically in showing 

 the persistency of germ B. 



VII. HISTORY OF GERM B.* 



Source — Micro-organism isolated from the college dairy milk, and is more or less 

 constantly present. 



Form and Grouping — Bacillus. It has a short rod with bluntly rounded ends. 

 There is a tendency to form short threads, yet it may be found single and 

 in pairs as often as in threads. It is very difficult to recognize the divisions 

 marking the individuals. 



Size — Length 1.75 — 5.25 microns. Diameter .58 — .875 microns. The maximum 

 length may be subject to much variation, owing to close union of bacilli in 

 threads. The cultures used for measurement were selected because of the 

 great freedom from thread formation. 



Protoplasm — A marked homogeneity of the protoplasm exists with meta-chro- 

 matic granules irregularly distributed. 



Pigment — An orange yellow pigment forms with the full development of the cul- 

 ture and in the presence of oxygen. The growth at first is a yellowish white, 

 gradually shading into orange yellow as further development takes place. 



Spores — No spore formation has been detected. 



Flagella — No flagella have been demonstrated. 



Motion — No motion Is visible. 



Staining — Readily stained with the common aniline stains. No special staining 

 methods have been found applicable. 



Temperature — Grows most vigorously at 30° — 35° C. Its range is wide, 15° — 39° 

 C. It is killed at 60° C. for 5 min. 



Colony — Colonies on gelatin plates start as small white dots, with microscopically 

 fringed borders which become more and more regular and better defined 

 as the colony matures. The colony rises from the surface, at first in a yel- 

 lowish white, creamy, semi-spherical mass, and little by little, as time passes, 

 turns to a deep orange color, becomes very flat, and the border is sharp. 

 There is little if any liquefaction of gelatin unless the moisture content of 

 the plate Is maintained to enable uncurbed development. There Is fre- 

 quently found, in planting this germ, a bunching effect which interferes 

 greatly with satisfactory counts. 



Stab Culture (gelatin)- — Growth spreads quickly over surface of gelatin. Lique- 

 faction takes place in funnel-shaped manner as soon as growth covers sur- 

 face. With liquefaction the growth appears as a thick scum on the surface 

 of the base of the funnel or cone, with little sediment at apex of the funnel. 

 The remaining liquefied gelatin remains clear with minute pieces of tenacious 

 particles or zooglea scattered through it. The funnel gradually works its 

 way towards the bottom of the tube, but several days are required at 20° C. 



Bouillon Culture — At first culture appears homogeneously cloudy; following this, 

 germs become adherent to glass at the sui'face, but no scum forms. There 

 is also a decided orange j'ellow sediment with the clearing of the supernatant 

 fluid. 



Agar Cultures — The growth begins as a yellowish white or creamy raised semi- 

 spherical mass, with no great inclination to spread much from point or line 

 of inoculation. The color of pigment develops into deep orange, often 

 passing through a lemon yellow from the creamy stage. In stab agar the 

 growth takes place very slightly below surface but is very abundant over it. 

 The germ does not appear sensitive regarding agar conditions for it develops 

 readily upon the varying agars used for laboratory purposes, as well as upon 

 whey agar, giving a luxuriant development upon each. 



Potato Culture — About the first evidences of growth will be found in a light, 

 shiny, moist, yellow mark appearin.g along line of inoculation. The creamy 

 aspect so constant in agar and gelatin is easily overlooked, for it has been in 



*Prof. H. W. Conn has worked out the history of this germ independently, and it will appear in his forthcoming treatise 

 on "Dairj" Bacteria." 



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