E. M. DoiDGE 59 



received from the same locality as before. From these a pure culture 

 was readily obtained, and a yellowish bacillus was isolated. With 

 these cultures an infection experiment was carried out; sound lemons 

 obtained from Warmbaths, where the disease does not occur, were 

 dipped in 1 : 1000 mercuric chloride and then w^ashed in running 

 water. They were then divided into four lots, each lot placed in a 

 large glass jar with a drop-on lid, and treated as follows: in jar (1) 

 the lemons were pricked with a sterile needle; the fruit in (2) was 

 lightly pricked with a very fine needle then atomised with a suspension 

 of an agar culture of the bacillus; in (3) the lemons were inoculated 

 by needle pricks, and in (4) were injected with a hypodermic syringe. 

 At first the lemons were kept at room temperature which even in the 

 day time was only 13° C. After 48 hours there were slight indications 

 of infection, the tissues in the immediate neighbourhood of the needle 

 pricks were sUghtly discoloured. 



After four days infections were quite marked, the oil glands in 

 particular were discoloured, and the tissues in the vicinity of the wound 

 were becoming shghtly depressed. The fruit was then removed to 

 the incubator at 25° C. the spots subsequently developed much more 

 rapidly and after ten days all the inoculated fruit showed well developed 

 infections. The fruit in the four jars may be described as follows: 



(1) Control, pricked with sterile needle, quite sound, wounds caused 

 by needle pricks barely visible on close inspection. (Plate V, a, right 

 hand figure.) 



(2) Pricked, then atomised with suspension of culture. There was 

 an infection for almost every needle prick. As many as 100 spots 

 on one lemon, the colour of the spots cinnamon buff to snuff brown 

 and mummy brown ; the diseased tissue sunken, and the spots small. 

 (Plate V, a and 6.) 



(3) Inoculated by needle pricks, spots up to 6 — 8 mm. diameter, 

 colour as in (2), from 20 — 65 sunken spots on each lemon. There was 

 a viscid drop of dirty yellowish substance oozing from the centre of 

 each spot; on examination this proved to be composed of capsuled 

 bacteria, and on being plated out, yielded a pure culture of the organism 

 with which the fruit liad been inoculated, (Plate VI, a.) 



(4) Suspension of culture in distilled water injected with hypo- 

 dermic syringe ; spots varied from 3 mm. to 30 mm. diameter ; they 

 were sunk 1 — \\ mm. below the surface, 4 — 32 spots on each fruit, 

 some of which did not appear to be in connection with a wound. The 

 discoloration varied from Sayal brown to mummy brown. Viscid 



