SITKA SPRUCE TREE AT FONTHILL ABBEV, 



67 



by Professor W. A. Craib, M.A., Lecturer in Forest Botany in 

 the University of Edinburgh, now Professor of Botany in the 

 University of Aberdeen, the results being recorded in his paper, 

 "The Regional Spread of Moisture in the Wood of Trees." 1 

 Professor Craib found that in a December-felled deciduous tree 

 the centre was the richest in moisture. In the present sample, 

 a conifer, felled in December, the maximum percentage of 

 moisture lay in the band of sapwood, and was more than double 

 that in the wettest portion of the heartwood. The maximum 

 percentage of moisture for the heartwood alone lay at the 

 centre, agreeing to that extent with Professor Craib's result for 

 a December-felled broad-leaved tree. 



" It is difficult to know whether to describe this Sitka spruce 

 as possessing a coloured heartwood or no. In the tree fresh 

 felled, there was easily apparent a sharply-defined, narrow band 

 of extremely wet sapwood, dingy white in colour, in marked 

 contrast to the brighter inner wood (which may be termed the 

 ripe wood). This outer, wet band gradually loses distinctness 

 on drying, and the timber throughout assumes a pinkish tint, 

 deeper in the centre and dying away to the circumference. In 

 the majority of planks of the sample, no exact distinction into 

 sapwood and heartwood can be made with the naked eye. 

 In some cases, however, the deepening in colour does stop 

 abruptly at the sapwood, the ripe wood being a pronounced 

 pink colour, while the sapwood is duller and paler. This 

 applies both to the artificially and naturally dried timber. 



" While the drums in the laboratory were green, the wet 

 band of sapwood was attacked by a mould {Ceratostomella 

 pilifera) which stopped short at the ripe wood. In this case 

 the sapwood is distinguishable owing to the 'blueing' caused 

 by the fungus. 



"The proportion of sapwood to ripe wood at various heights 

 was as follows, the figures representing the average of measure- 

 ments along the longest and shortest radii at each height : — 



' Craib, in Notes, Roy. Bot. Gard. Edin., xi. p. i (1918). 



