DESCRIPTION OP^ THE LEAF-SPOT ORGANISM. 11 



Beef houillon. — Peptonized beef bouillon + 15 lield at 24° to 25° C, 

 if inoc-iilated from young, vigorous bouillon cultures, clouds thinly 

 in 6 hours and is moderately to heavily clouded in 24 hours. The 

 growth is best at the surface, where a white layer is formed. This is 

 not a true pellicle, as it disintegrates when the cultures are handled.* 

 No zoogloeae are present. There is no rim. In two days there are 

 heavy^ clouds and a moderate amount of white flocculent precipi- 

 tate. After several weeks the precipitate is white and slimy, mod- 

 erate in quantity, and with small crystals in it. The medium 

 becomes shghtly greenish. After several months the precipitate is 

 viscid. 



Add houillon. — In neutral beef bouillon plus vegetable acids, 

 growth occurs until an acidity of +34 for oxalic acid and +36 for 

 malic and citric acids (Fuller's scale) is reached. There is no rim or 

 pellicle. Occasionally pseudozoogloeas are formed in the more acid 

 media. 



Microscopic examination shows most of the organisms greatly 

 reduced in length, some so short as to be spheroidal. That these 

 were not contaminations was proved by plating out and by tests on 

 other culture media. 



Alkaline houillon. — In alkaline beef bouillon (NaOH used) the 

 organism grew well in — 17, — 19, —22, less in —23, and not at all in 

 — 25, —26, and —28 (Fuller's scale). Involution forms and filaments 

 were present in — 17 beef bouillon when two weeks old. 



Bouillon with sodium cJihrid. — In beef bouillon plus 2 per cent NaCl 

 the growth is as good as in plain beef bouillon. With the addition of 

 more NaCl the growth graduallj^ lessens until it is scarcely noticeable 

 in a 5 per cent solution. When grown in a 4 per cent solution, the 

 organism is not motile. In a 2 per cent solution, the organism is 

 motile, but less so than in beef bouillon without NaCl. 



Beef houillon over chloroform. — For the first 24 hours the growth is 

 somewhat retarded. By the end of 48 hours no difference could be 

 seen between cultures over chloroform (5 c. c. of chloroform with 10 

 c. c. of beef bouillon not shaken) and those in plain beef bouillon. 



Loeffler's hlood serum. — Growth of stroke is moderate, smooth, 

 shining; color creamy; margins finely crinkled. No liquefaction. 

 After three months the whole medium was slightly browned. 



Cohn's solution. — Moderate clouding and white precipitate; no rim, 

 pellicle, or zoogloese; no fluorescence. After some weeks feather- 

 like crystals of considerable size (5 to 10 by 2 to 6 mm.) are formed. 



Fermi's solution. — ^loderate clouding at first. Precipitate mode- 

 rate to abundant, white, flocculent. Pellicle white, tender, sinking 

 in strings and masses. Finally the medium is densely clouded and 



' Old cultures kept for several months at 0.5° to 1.5° C. had a delicate pellicle. 

 225 



