NOTES AND ABSTRACTS. 



269 



The bacteria that produce gum diseases in stone-fruits can be com- 

 bated by the same means. The practical gardener scrapes off the gummy 

 exudation and applies sorrel leaves to the wound. The oxalic acid 

 expressed from the leaves acts as an antiseptic and destroys the bacteria. 

 But it is possible to produce immunity by extra-radical treatment, such 

 as the introduction of very weak solutions of creasote or organic acids. 

 In like manner the bark can be rendered immune from, and actually 

 antagonistic to, the attacks of insects. The remainder of the article 

 treats of spraying, which induces increased absorption as well as tran- 

 . spiration. The author suggests that the liquids used in this manner to 

 destroy pests might be compounded so as to serve the double purpose of 

 food and insecticide ; if, for example, potash were employed, instead of 

 soda, in the well-known spray of copper sulphate, sodium carbonate, 

 and water. — F. A. W. 



Plaster (Sulphate of Lime) as a Dressing* for Fruit Trees. By 



Jean Beziat {Le Jardin, vol. xx. No. 454, p. 23 ; January 20, 1906). — Acts 

 as a valuable intermediary in the absorption of potash from the soil. The 

 sulphate of lime reacts with the potassium carbonate of the soil, forming 

 soluble potassium sulphate, which is readily absorbed by the roots. 

 Fifteen to twenty kilogrammes should be spread per acre (between one 

 and two quarters per acre) in February and March, and ploughed in. 



F. A. W. 



Poisonous Haricot Beans. By Hortulus {Le Jardin, vol. XX. 

 No. 458, p. 84 ; March 20, 1906 ; with several figures). — The consumption 

 of haricot beans from Phaseolus luneatus induces symptoms of poisoning 

 from prussic acid, due presumably to the action of the ferment emulsin 

 upon the glucoside amygdalin in presence of water. No trace of prussic 

 acid is discoverable in species indigenous to Europe ; exotic novelties 

 should accordingly be avoided. — F. A. W. 



Potato, Orig'in of the. By P. Harlot {Le Jardin, vol. xx. 

 No. 454, p. 21 ; January 20, 1906). — Solanum tuberosum appears to be 

 a hybrid form derived from the two species S. Commersoni and S. Maglia. 



F. A. W. 



Potatoes, Quality in. By J. W. Gilmore {U.S.A. Exp. SUi. 

 Cornell, Bull. 230; June 1905; 13 figs.). — The author concludes that 

 the culinary and dietetic values of potatoes are ''not dependent upon 

 chemical composition so much as upon the anatomical (and perhaps 

 physiological) characteristics of the tuber and the arrangement and 

 distribution of starch and water areas in its substance. The structural 

 characteristics of the tuber are influenced by the conditions of the soil " 

 and the atmospheric conditions under which the potatoes grow. He 

 considers that the daily range of soil and atmospheric temperature 

 during the growing period, the degree of ripeness of the tuber when the 

 plant dies, and the physical condition and type of soil all influence the 

 mealiness of the potato when boiled, and to a considerable extent the 

 flavour. In the summary it is recommended that the sets should be 

 planted five or six inches deep. If planted deeper the moisture and 

 temperature conditions are unsuitable for the development of tubers on 



