170 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



If insects are excluded from a tomato house by means of insecticides 

 there is a danger of the fruit not being fertihsed, when it remains quite 

 small and seedless. This danger is also brought about in some instances 

 by keeping the house too damp, the pollen becoming sodden with 

 moisture, and not reaching the stigma to effect fertihsation. 



Fig. 41. — Tomatoes, showing a Bacterial Disease, grown at Wisley. 



In those districts in France where the disease is prevalent it is not 

 difficult to account for the presence of bacteria that could be conveyed by 

 insects for starting the disease ; but where the bacteria came from that 

 caused the disease at Wisley is a problem that has yet to be solved. 



Seed from Diseased Tomato Plants. 



An idea is prevalent amongst practical men that the use of tomato 

 seed produced by diseased plants is attended with risk. This applies to 

 the prevalent tomato diseases, "black rot" or "black stripe" (Macro- 

 sporium solcmi), "sleeping disease" (Fusariuin lycopersici), and "leaf 

 rust " {Cladospormm fiilvwn). If this condition of things were possible 



