GREENHOUSE AND COLD FRAME FUMIGATION 135 



cess, only a few treatments during the season being 

 required. Leaf-eating larvae, slugs, millipedes, cut- 

 worms, etc. , when exposed are killed as well as plant- 

 lice. Red spiders, however, are not entirely eradicated 

 by the treatment. The foliage of single violets, like 

 California and Princess of Wales, are sometimes slightly 

 injured by the stronger dose of gas. A weaker dose, 

 one-tenth of a gramme potassium cyanide per cubic 

 foot, should be used when they are to be treated. 



Other plants. Other plants on which the gas has 

 been tried on a small scale indicate that it may prob- 

 ably have quite a wide range of usefulness. It has 

 been used on the following plants at the rate of one- 

 tenth gramme of cyanide per cubic foot of space for 

 twenty minutes without injury. Further experiment, 

 however, is necessary before the treatment can be 

 recommended for these: Alocasia macrorhiza variegata; 

 Anthurium crystallinum; Areca lutescens; Aralia filici- 

 folia; Adiantum cuneatum; Adiantum ballii; Campy - 

 lobotrys refulgens; Cissus discolor; Cretans (in variety)/ 

 Cichorium intybus; Diffenbachia lenmannii; Ficus elas- 

 tica ; Fuchsias (in variety) / Jacaranda mimosczfolia / 

 Marantas (in variety) / Nymph&a candidissima, and 

 odorata rosea; Pontederia crassipes; Pandanus veitchii; 

 Phrynium variegatum; Phyllotcenium lindenii; Panax 

 victories; Stenanthium lindenii. 



Roses. Perle des jardins, Mermet, and Bride. 

 The young growth on roses is particularly sensitive, 

 and has been more or less injured in all our experi- 

 ments. 



Carnations. Scott, Garfield, Meteor, and Me- 



