154 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of this genus is Sisyrinchium, from which it differs by having free filaments. 

 O. chimboracensh grows well in a cold greenhouse and sets seed freely. Flowers 

 lavender blue. — L. C. E. 



Peppermint Oil, The Effect of Cultural and Climatic Conditions on the Yield 

 and Quality of. By F. Rabak (U.S.A. Dep. Agr. Bur. PI. Ind., Bull. 454, Dec. 9, 

 191 6 ; 16 pp. ; 7 tables). — The peppermint plant, Mentha piperita L., is ex- 

 tensively cultivated as the source of a volatile oil used as a flavouring and thera- 

 peutic agent. The value depends much upon the composition. The principal 

 ester constituent, menthyl acetate, possesses a very fragrant minty odour, to 

 which the agreeable aroma of the oil is largely due. The alcoholic constituent, 

 menthol, possesses the well-known penetrating minty odour and characteristic 

 cooling taste. The flavouring properties of the oil are due largely to both the 

 ester and alcoholic constituents, while the medicinal value is attributed to the 

 latter only. Plants were grown under various conditions during the years 

 1908 to 1912, and the following conclusions were arrived at. 



Conditions of soil and climate are influential factors in the formation of the 

 oil. Light sandy or loamy soils appear to be the most favourable for the pro- 

 duction of an oil of high quality. 



The yield of oil distilled from fresh plants apparently decreases as the plant 

 matures. Drying the plant before distillation results in a considerable loss of 

 oil. The largest proportion of oil is found in the leaves and flowering tops. 



The percentage of esters in the oils increases as the plants approach maturity. 

 The menthol content of the oil bears a close relationship to the ester content. 

 The free acidity and ester content of the oil distilled from dry plants is con- 

 siderably higher than in the oil from fresh plants. The drying of the plants 

 causes changes favourable to esterification, while the percentage of free and 

 total menthol in oils distilled from dried plants is also uniformly high. 



The formation of esters and menthol takes place most readily in the leaves 

 and tops of the plant, the metabolic processes showing increased activity as the 

 plant matures. 



The effect of shade upon the plant is to decrease esterification and the form- 

 ation of menthol, and is due possibly to the lessened activity of the elimination 

 of water by the plant. 



The action of frost noticeably increases esterification and the formation of 

 menthol. — F. G. A. 



Phaius grandifolius in Panama. By R. A. Rolfe (Orch. Rev. xxvi. pp. 219- 

 220). — An account of the discovery by Mr. C. W. Powell of this well-known 

 Chinese species in Panama. The circumstances of its introduction are not 

 known, but it is shown that the species is now thoroughly naturalized and 

 abundant in Jamaica. — R. A. R. 



Pheasants and Agriculture. By Miss A. F. C.-H. Evershed (Jour. Agr. Sci. vol. 

 ix. Part 1 ; Aug. 1918). — At the request of the East Anglian Game Protection 

 Society, the author examined the contents of the crops of 311 pheasants supplied 

 by members of the society month by month throughout the year 191 4. Full 

 details are given of the roots and stems, weed leaves, weed seeds, flowers, agri- 

 cultural seeds and insects found in each crop. In the words of the author, 

 "119 crops contained cereal grains or agricultural seeds of some sort, but a 

 careful consideration of them seems to reduce the real cases of injury to 12 birds, 

 there being good evidence in the remaining cases that the corn was either hand- 

 fed or picked up in stubble. The damage done by pheasants to growing agri- 

 cultural crops seems almost negligible." — /. E, W. E. H. 



Pilea Forgeti N. E. Br. (Bot. Mag. t. 8699 ; Feb. 191 7). — This new species 

 was introduced by Messrs. Sanders' collector, Mr. L. Forget, from Venezuela in 

 1914. The plant is dwarf with broadly lanceolate leaves, beautifully coloured 

 with longitudinal stripes of various shades of green and bronze, and reddish 

 beneath. The female flowers are inconspicuous, but the small staminate flowers 

 are borne in dense many-flowered clusters on erect peduncles about 3 in. long. 

 A tropical-house plant. — F. J. C. 



Pine District, Entomological Notes on the Surrey. By B. W. Adkin, 



F.E.S. (Quar. Jour. For. xi. pp. 217-237, Oct. 1917). — Sirex gigas L., the Giant 

 Wood-wasp, has larvae which bore into the stems of pine and fir trees, especially 

 if the trees are sickly. The species is not very common, but is widely distributed 

 and frequently occurs in the Surrey Pine District. 



S. juvencus L., the ".Steel-blue Wood- wasp, another wood-boring species, 

 is recorded in many books as a common British insect. These records appear 

 to be erroneous for the Rev. F. D. Morice states that he knows of only two 



