310 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Toxic Excreta of Plants. By F. Fletcher, M.A. [Jour. Agr. 

 Sci. iv. pp. 245-247; Jan. 1912). — The writer has already pointed out 

 that Sesamum indicum seedlings die when they have reached a height 

 of a few centimetres if planted at a distance of two feet from Sorghum. 

 This was observed at Surat on black cotton soil of a retentive nature 

 in a district with a rainfall of 42 inches per annum. A series of experi- 

 ments carried out at Gizeh in Egypt, where the rainfall is zero and the 

 water supply under control, corroborate the idea that the grass pro- 

 duces a substance poisonous to Sesamum. Maize and sesamum were 

 sown in alternate rows, and an account of the method of treatment 

 of the plants is given. The result was that the sesamum between two 

 rows of maize remained very small, while that with a row of maize 

 on one side did not attain a third of the size of isolated plants. — F. J. C. 



Transplanting, Unintentional. By H. S. Coward (Bot. Gaz., pp. 80- 

 84 ; Jan. 1913 ; with 2 rigs.). — The author found 60 species of flowering 

 plants and a fern developing on an apparently denuded area near 

 Cold Spring Harbour. Of these 39 were long-lived perennials and 

 had been unintentionally transplanted through pieces of root or 

 rhizomes. Small pieces of roots of Myrica, Sassafras, Rubus, Robinia, 

 Lespedeza, Rhus, and Asclepias gave rise to new plants. Aralia 

 nudicaulis, Smilax, Lespedeza grew from pieces of the rhizome. During 

 resting period of vegetation most plants can be transplanted even by 

 very rough methods. — G. F. S. E. 



Tree-Growth. By Harry P. Brown [Bot. Gaz., pp. 386-403 ; Nov. 

 1912 ; with 2 plates). — The " cambial awakening " began in Pinus 

 rigida at Ithaca, New York, as early as April 15, which agrees with 

 general observations in middle Germany, where it has been noted on 

 ten-year-old Scotch fir on April 20 (it is generally supposed to begin 

 between latter half of April and first half of May). Larch and White 

 Pine begin last week in April. 



Most authorities state that growth begins first in the youngest 

 branches and makes its way slowly downwards. The author finds 

 that it begins first (in Pinus rigida) some distance below the apex, 

 but in nineteen days gradually spreads upwards and reaches the apical 

 shoot. It may take a long time to reach the base of the tree, especially 

 if it is old, surrounded by vegetation, and covered with thick bark. 



Growth in the branches follows the same rule and their cambium 

 awakes at almost the same time, but growth of the lateral shoots 

 lags behind that of the main stem. 



The most rapid increase in diameter occurred on the terminal 

 shoot between June 6 and 15, and elsewhere May 25 to June 6. 



The width of the complete ring decreases from apex to base ; the 

 living portion of the cortex reverses this rule. 



No appreciable difference was recorded between the times of 

 awakening on the north and south sides of the tree. — G. F. S. E. 



