()0 



A Bactet'kd Spot of Citrus 



drops of bacterial slime were also oozing from the centre of these spots. 

 (Plate VI, 6.) 



An infection experiment on a larger scale was carried out with a 

 quantity of citrus fruit obtained from the Government Orchard at 

 Warmbaths; the fruit was picked from the trees in the writer's pre- 

 sence, taken direct to the Laboratory in boxes and the inoculations 

 carried out two days later. There was no trace of the disease on any 

 of the fruit in the orchard. 



The cultures used were from four different sources: from natural 

 infections on lemon, on orange and on naartje and from an artificial 

 infection on lemon. In the schedule the last is distinguished as lemon II, 

 the first as lemon I. In each case young cultures on nutrient agar were 

 employed for needle prick inoculations, and young cultures suspended 

 in sterile distilled water for atomising. 



All controls were pricked with a sterile needle; inoculations were 

 carried out in four different ways, some were atomised with a " glaseptic " 

 sprayer without any previous wounding, others were lightly pricked with 

 a very fine steel needle and then atomised, into a third lot of fruit the 

 organism was introduced by means of needle pricks, and the bacillus 

 was injected into a fourth set by means of a hypodermic syringe. 



No. of 

 I'ruit 



6 



7 

 8 

 7 



8 



Kind of Fruit 



Ripe lemons 



Green ,, 



Ripe „ 



Green ,, 



Ripe ,, 



Green ,, 



Ripe ,, 



Ripe ,. 



Green ,, 



Ripe ,, 



Green ,. 

 Ripe 



Green „ 

 Navel oranges 



Valencia late orantjes 



Source of 

 Culture 



Lemon 1 



i 



I 



.. 1 



., I 



., I 



Orange 



Lemon I 

 Orange I 

 Lemon I 

 Orange 

 Lemon I 

 Orange 



Method of Inoculation Result 



.Sterile needle ... ... No infection 



Pricked then atomised Positive 



Needle pricks ... ... ,, 



Hypodermic syringe ... „ 



Sterile needle ... ... No infection 



Piicked then atomised Positive 



Needle pricks ... ... „ 



Ifypodeiinic syringe ... „ 



Sterile needle ... ... No infection 



Pricked then atomised Positive 



Needle pricks ... 



Hy])o<leiniic syiinge 



Steiile needle ... ... No infection 



