SCHUSTER'S GERMAN POTATO ROT. 273 



Cultures in bouillon containing methylenc blue (0.2 c.c. bouillon-culture: i : 1,000 m. b.), lost 

 their virulence on exposure to diffuse daylight for 4 hours, while similar cultures kept in the dark 

 showed an increasing virulence. The methylene blue in i per cent quantity in bouillon is reduced in 

 3 to 4 hours. 



Indol occurs (distinct in bouillon after 10 days). Hydrogen sulphide is produced slowly. 

 Nitrates are reduced. The organism liquefies gelatin, but not rapidly. It does not liquefy blood- 

 scrum. It acts on starch slowly and incompletely. It grows best at 35.5 C. [see below]. The 

 range of temperature is not known. Schuster says slight growth at 2 C. and at 40 and 44 C. Good 

 growth at 27.5 C. and pretty good at 36 C. Moderate at 37 C. and at 17.5 to i8.5C. Growth at 

 all temperatures from 16 to 2 C. is recorded as slight. The organism is aerobic and facultative 

 anaerobic. Schuster gives a table of its action on sugars, alcohols, etc., but I am not able to make 

 much out of it, except that cane-sugar, grape-sugar, milk sugar, arabinose, mannit, peptone, and 

 asparagin favor growth, whereas ammonium chloride, ammonium phosphate, ammonium tartrate, 

 ammonium sulphate, glycerin, caffein, arbutin, potassium nitrate, potassium phosphate, citric acid, 

 potato starch, and cellulose do not. With ammonium chloride and the substances named immediately 

 thereafter, there was a weak growth, with those italicised there was no growth whatever or only 

 the slightest. These experiments were made in flasks in 100 c.c. portions of Arthur Meyer's nitrogen- 

 free mineral solution* to which were added usually 10 grams of the substance to be tested (caffein 

 0.3 gr., arbutin 3 gr.). Cane-sugar, glycerin, mannit, and asparagin gave pellicles and no precipitate; 

 grape sugar and arabinose gave pellicles and precipitate; milk sugar and peptone gave clouding 

 and precipitate without pellicle. These flasks were each inoculated with one loop from a bacterial 

 suspension of a 24-hour agar-culture and were kept at about 20 C. 



Gas is not produced from dextrose. At room temperatures milk is slowly coagulated (eighth 

 day) and the curd is peptonized, but at 34 C. these changes did not occur. At both temperatures the 

 upper layers (Fettschicht) became greenish-yellow. 



If a trace of sodium selenite is added to gelatin which is then inoculated with this bacterium the 

 culture becomes blood-red in 12 hours. 



This organism causes in nutrient agar a greenish-yellow fluorescence. 



On agar-plates the surface colonies are circular, slightly raised, thinning at the edges, fine 

 granular, with a denser center. The buried colonies are smaller and not characteristic. 



On alkaline agar-strokes the growth is visible in 24 hours ; it forms along the needle track a dry, 

 thin, yellow- white to greenish layer, exhibiting a large number of cross-folds forming a wrinkled mem- 

 brane. In thick sowings the folds may be lifted up vertically a millimeter above the surface, and the 

 layer is then moist and watery or slimy [see below). 



In agar-stab-cultures there is only a slight growth along the needle line. This is best at the 

 point of entrance where after 2 or 3 weeks there is a thick mulberry-shaped piling up of yellowish 

 bacterial masses while the surface is covered with a white skinny layer. 



On Appel's slant potato-juice-agar there was a very abundant development of the yellowish-gray 

 bacterial masses within 24 hours which later fused into a thick slimy layer. 



In the expressed juice of cooked carrots, with 2 per cent agar, there developed along the lower 

 part of the streak a scanty growth in the form of a thin, white, weak, moist layer. 



On gelatin plates very small colonies in the form of round drops appear in i to 2 days. Lique- 

 faction begins in 48 hours as a pit in which the nearly smooth-edged colony floats in the form of small 

 lumpy masses lying one over the other. The center of the colony is considerably thickened and dark 

 brownish. The buried colonies are globose, granular, and liquefy more slowly. 



In gelatin-stab-cultures near the surface there is a funnel-form liquefaction extending gradually 

 to the walls of the tube and not far downward along the needle track, where growth is slight. Judg- 

 ing from Schuster's figures liquefaction the first day is in the form of a narrow (steep) funnel ; that on 

 the eighth day touches the walls and resembles a champagne glass, i. e., the liquefaction is restricted to 

 the upper quarter of the tube. Sometimes, however, after very copious inoculations there appeared 

 along the needle-track liquefaction centers where clumps of bacteria developed, but elsewhere the 

 needle-track was very little changed. 



In Appel's potato-juice gelatin (Arb. Kais. Biol. Anst. HI, p. 396) there was rapid growth in stab- 

 cultures with intense liquefaction, the entire contents of the tubes being liquefied within a few days, 

 the bacteria being heaped up in an irregular globose mass on the bottom of the tube. The non-motile 

 organism already referred to liquefied gelatin more slowly. 



In neutral nutrient bouillon a strong general clouding takes place within 24 hours. A white 

 pellicle forms on the surface and the fluid is filled with small particles (Krumeln). There is a copious 

 white precipitate which on shaking holds together. Grape-sugar bouillon is very favorable for the 

 growth of this organism. It did not grow well in beer. 



Distilled water, 1,000; KH,PO,. i.o; CaCIA i.o; MgSO 4 + 7 HA 0.3; NaCl, o.i; Fe,Cl,, o.oi. 



