April 1891.] E0TA2sUCAL SOCIETY OF EDINBURGH. 93 



volume of trees, and thus know whether it is more profitable 

 to fell or retain them. 



Then, from a scientific point of view, the instrument may 

 be employed for determining the commencement, progress, 

 and conclusion of growth as affected by species, weather, 

 elevation, exposure, &c. Lately it has been much used by 

 Hartig and others in connection with pathological experi- 

 ments. With its assistance the wood of a healthy tree can 

 be easily infected with the mycelium of a destructive fungus, 

 and then the progress of the latter can be watched, and its 

 effects noted. To do this it is necessary to take a small 

 cylinder of wood from the infected area of a diseased tree, 

 and, having removed a corresponding cylinder from a sound 

 tree, the former, w^ith the contained mycelia, is substituted 

 for the latter, and a little grafting wax is applied to the 

 wound to prevent the evaporation of water. 



By experimenting in this way, too, it can be proved 

 whether an unhealthy tree is really suffering from a fungus 

 which may be present upon it, or whether the latter is not 

 merely a secondary phenomenon. 



On Tempeeature and A^egetation at the Eoyal 

 Botanic Garden, Edinburgh, during the month of 

 March 1891. By PiObert Lindsay, Curator of the Garden. 



March has been the most severe and trying of any month 

 this winter. The thermometer was at or below the freezing- 

 point on twenty occasions, the total amount of frost for the 

 month was 130° as against 49° for the corresponding month 

 last year. The lowest readings occurred on the 9th, 15° ; 

 10th, 15°; 12th, 19°; 13th, 20°; 14th, 19°. The lowest day 

 temperature was 38° on the 10th, and the highest 57° on the 

 1st. Vegetation, generally, has made very little progress. 

 Deciduous trees and shrubs are scarcely any further advanced 

 than they were at the close of last month. The flower buds 

 of Rhododendron Nohleanum and R. precox were completely 

 destroyed by frost on the 9th of the month. A good many 

 plants have suffered severe injviry. Stocks and wallflowers 

 have been nearly all killed. Several species of Cistus, 

 Ceanothus, Eumhjptus, Olearia, and shrubby Veronica are 



