124 ''Sleepu Disease" of the Tomato 



over calcium chloride in vacuo. When dry, an equal weight of clean, 

 dry quartz sand was added, and the material ground in a mortar. The 

 dry material was extracted for 1 hour with sterile water, using 0-2 g. 

 mixture to 3 c.c. water. The extract was tested for the presence of an 

 endo-enzyme capable of producing wilt, but without success. 



Exo-enzyme. 



The turnip juice filtrate from the germinated spores was tested in 

 two ways. In the first instance part was de-activated by raising the 

 temperature to 100° C. and part untreated. Seedlings 6 inches high were 

 cut off near the base under water and placed in the active and de- 

 activated solutions. Others were also placed in the original turnip juice 

 as controls. All liquids caused wilt in 20 minutes owing to their high 

 osmotic pressure. They were diluted to three times their bulk with sterile 

 water and the experiment repeated. The active solution caused wilt in 

 25 minutes, the de-activated solution in 105 minutes and the original 

 turnip juice in 5 hours. Another portion of the original filtrate was 

 treated with absolute alcohol until no further precipitation took place. 

 The precipitate was allowed to settle, dried over-night, and taken up 

 with sterile distilled water the next morning; part being left untreated 

 and part de-activated at 100° C. Seedlings cut off at the base and 

 seedlings with roots which had been thoroughly washed in running water 

 were placed in the solutions. Wilt was produced in the cut seedHngs but 

 • not in those with roots, the active solution producing a distinct wilt in 

 31 minutes, and the de-activated solution in 4 hours. Similar experi- 

 ments were carried out with the extract from the ground mycelium, but 

 no wilt was observed in any case. 



The above experiments were repeated several times with precisely 

 the same results. The wilted seedlings were sectioned and examined after 

 24 hours' treatment. Those wilted by the active solutions showed a 

 browning of the wood for 5 cm. up the stem. Microscopical examination 

 showed the presence of a brown gum in parts of the wood and near the 

 end of the stem the cambium was destroyed. The seedlings in the de- 

 activated solutions were soft at the end, but the wood was not browned ; 

 there was no gum, and no dissolution of the cambial layers. 



The above results appear to warrant the assumption that under 

 certain conditions a definite exo-enzyme is produced by V. albo-atrum 

 capable of producing wilt. Such an enzyme may act directly in virtue 

 of its function as an enzyme, or indirectly by reason of its gum-producing 

 powers. It can be precipitated by absolute alcohol and dried. When re- 



