420 A Tomato Canker 



Cultural Characters. 



Preliminary cultivation was carried out as suggested by the Society 

 of American Bacteriologists. In all cases, unless otherwise stated, cultures 

 were incubated at 30° C. 



Plate cultures on nutrient agar + 15. Colonies show as minute, shining 

 points after 48 hours. By the third day they have increased somewhat 

 in size, and are coppery, translucent by transmitted light, and yellowish 

 or somewhat opalescent by reflected light. There is seldom any de- 

 velopment after the fourth day; on thinly sown plates fully developed 

 surface colonies are circular or oval, up to 5 mm. diameter, semi-translu- 

 cent, colour Naples yellow (XVI). The margin is entire and texture 

 homogeneous, finely granular as seen under the low power of the micro- 

 scope. In some there is a faint indication of concentric zoning, but this 

 is more evident in the bluish white colonies about 2 mm. in diameter, 

 formed between the agar and the bottom of the plate. Long feathery 

 crystals begin to form in the medium after about ten days. Submerged 

 colonies are minute and lenticular, and often form surface colonies by 

 excentric development. 



Streak cultures on nutrient agar + 15. After 24 hours the streak is 

 smooth, slightly convex, wet-shining, with entire margin, and about 

 5 mm. broad. The growth increases somewhat up to the third or fourth 

 day, entirely covering the wetter part of the medium at the base of the 

 tube. The colour is Naples yellow, and growth shows irregular, semi- 

 opaque streaks when held up to the light. There is a heavy growth in the 

 condensation water. Crystals begin to form under the streak at the 

 end of the first week. 



Stab cultures in nutrient agar +15. Surface growth only; no growth 

 in the depths of the medium. 



Shake cultures in nutrient agar + 15. Numerous surface colonies de- 

 velop and become confluent, entirely covering surface. There are some 

 very minute submerged colonies just below the surface but none in the 

 depths of the medium. 



Plate cultures on nutrient gelatine +15. All gelatine cultures were 

 incubated at 20-22° C. Colonies were visible on the third day; on the 

 fourth day thickly sown plates were partly liquefied, on more thinly 

 sown plates surface colonies were up to 1 mm. diameter, convex glistening, 

 cream colour, translucent, context homogeneous and finely granular; 

 submerged colonies minute, opaque, lenticular. On the sixth day thickly 

 sown plates were completely liquefied; ui more thinly sown plates the 



