NOTES AND ABSTRACTS. 269 



For truck and garden plants, lye-sulphur wash and the same 

 remedies as for the greenhouse, with the addition of clean gardening 

 or farming, early fall ploughing, keeping down weeds, and crop rota- 

 tion where practicable. — V. G.J. 



Respiration of the Orgrans of Vascular Plants. By G. Nicolas 

 (Ann. Sc. Nat. vol. x. Nos. 1-3, pp. 113). — In normal respiration 

 (N) the leaves of a plant have greater respiratory intensity and a lower 

 respiratory quotient than the petiole, stem, and root. Bespiratory 

 intensity is defined as the oxygen absorbed by 1 gram of material an 



CO 



hour. The respiratory quotient, , is obtained by dividing the 



carbonic acid liberated per gram per hour by the oxygen absorbed per 

 gram per hour. The intramolecular respiration (I) was determined by 

 observing the gaseous changes which ensue when different parts of a 

 plant are placed in an atmosphere which does not contain any oxygen. 

 Under these conditions the leaves do not liberate more carbonic acid than 

 other parts of the plant. As a rule the leaves give off less carbonic acid 



than in ordinary air. generally approximates ^. A coating of 



vaseline on the lower surface of the leaves diminishes the normal respira- 

 tion to ^ to y\-, but the transpiration is reduced from to -^^ of its 

 normal value. Hence the author concludes that respiration takes place 

 through the cuticle and transpiration through the stomata. Green leaves 

 are slightly more active than etiolated leaves. — S. E. W. 



Rhizoctonia violaeea causing- a New Disease of Trees. By 



Dr. W. Somerville (Quart. Jour, of Forestry, vol. iii. 2, p. 134). — 

 Eeports the occurrence of Rhizoctonia violaeea (the " copper web " 

 fungus) on the roots and lower part of the stems of oaks and Scots 

 pine, which were killed by it. The fungus has hitherto been known to 

 attack lucerne, clover, potatos, carrots, mangolds, and crocuses, and 

 causes considerable damage to them ; but until now it has not been 

 recorded on trees. — F. J, C. 



Rhodazalea, New. (Jour. Soc. Nat. Hort. Fr. Aug. 1909, 

 p. 487). — Messrs. Croux, who produced the hybrid known as Rhod- 

 azalea Crouxii, are now showing a double variety of * Ehodazalea, ' 

 produced by crossing Azalea mollis with Rhododendron ' Marie van 

 Houtte.' Among their collection of Ehododendrons are several good 

 new varieties — ' Mme. Emile Fessard,' ' Mme. Yvonne Delchelpe,' 

 * M. Emile Salacroup,' etc. — M. L. H. 



Rhododendron Keiskei. By W. B. Hemsley (Bot. Mag. tab. 

 8300). — Nat. ord Ericaceae; tribe Rhodoreae. Japan. Shrub 3-7 ft. 

 high. Leaves biennial, coriaceous, 1^-3 in. long. Flowers yellow^ 

 lf-2 in. across. — G. H. 



Rhododendrons, Chinese-Thibetan. (From the Bull. Soc. 

 Nat. d'Acdimat. Fr.) (Jour. Soc. Nat. Hort. Fr. Nov. 1909, p. 696).— 



