70 A Bacterial Spot , of Citrus 



the centre, and concentric rings are visible by transmitted light; 

 under the low power of the microscope they are grumose in the centre 

 and coarsely granular near the edge ; in colour they are dirty yellowish 

 white. After five days the diameter has increased to 5 mm., and the 

 colonies have a number of distinct concentric zones, by transmitted 

 light the two central zones are yellow and the remainder bluish white. 



Lemon and orange glucose agar streaks'^ are dirty yellowish white, 

 glistening, very slightly raised, 3 — 10 mm. broad, and the condensation 

 water is rather heavily clouded. On the lemon glucose agar the streak 

 had a shagreen surface, on orange glucose agar the surface was smooth 

 but moruloid in the centre. 



Orange laevulose agar. Streaks on this agar are similar in character 

 to those on orange glucose agar but are considerably more luxuriant. 



Beerwort agar. The organism grows very well on this medium, 

 it forms a shining streak with a convex central portion and a fiat 

 margin with a slightly undulate edge; the breadth of the central 

 portion is 4 — 5 mm., of the margin 1 mm. There is a copious yellow 

 growth in the condensation water. 



As it dried up the surface of the raised central part becomes corru- 

 gated and it is decidedly viscous. 



Bean agar is a fairly good medium, streaks are smooth, yellowish, 

 somewhat umbihcate, and about 3 mm. diameter. 



Cabbage agar. A very characteristic growth forms on streaks of 

 ^ cabbage agar. It is not very abundant and consists of a number of 

 spherical, opaque, yellowish colonies standing up above the surface 

 of the medium, and disposed irregularly in a flat translucent streak 

 1 — 4 mm. wide. The surface of the agar becomes conspicuously 

 whitened in the vicinity of the streak. 



Loeffler^s blood serum is not liquefied, the organism forms a shining 

 yellow growth along the needle track. 



Starch jelly. No growth. 



Nutrient gelatine colonies are just visible to the naked eye after 

 24 hours at 20° C. as minute glistening points. In two days they 

 attain a diameter of 1 — 3 mm., and are round, ghstening. slightly 

 convex, coppery by transmitted Ught, creamy by reflected hght. Under 

 the microscope they are rather coarsely granular and inclined to become 



^ Orange or Lemon glucose agar was made as follows : 50 grammes of fresh rind was 

 hoiled for 30 minutes with 500 c.e. distilled water, filtered, then 10 irrs. dextrose added 

 and solidified in the usual way with 1'5 agar powder. 



\n Orange laevulose agar, lae\ ulose was substituted for' glucose. 



I 



