64 Reuben T, Patton : 



the year. In other words, we are concerned with the quantity oC 

 moisture and its distribution both in space and time. 



If the sapwood be the means by which water is transported in a 

 living tree, then it should not matter at what time of the year a tree 

 is felled, and if the heartwood be inactive, then we should expect the 

 heartwood content to be a constant. It is obvious, however, that it 

 the heartwood content does undergo a seasonal change, then there 

 is a favourable period for felling. Ordinarily, however, when we speak 

 of the sap as rising, we are considering only the sapwood, and not the 

 heartwood. 



It has recently been suggested (1) that the heartwood may play 

 an important part in the moisture needs of the plant. It is suggested 

 that the heartwood acts as a reservoir for the sapwood. This may be- 

 true for some trees, but it cannot hold for all. The giant eucalypt 

 of Victoria, E. regnans, may have practically no heartwood at all, as. 

 it may have all rotted away, yet the tree may live for centuries. 

 The trunk is a mere shell, yet the reeds of the tree are met. It was 

 quite a well-known belief among the tree-fellers in the Victorian 

 forests that the central portion of the heartwood of our big trees con- 

 tained more moisture than the outer portion of the heartwood. In. 

 many cases it was found that this central portion contained more 

 moisture than the sapwood. This central portion is very prone to 

 decay, and is rejected in timber milling. An examination of it micro- 

 scopically shows that the fibres have comparatively thin walls. The 

 percentages of moisture for one tree were as follow: — 



Central portion 150 per cent. 



Outer heartwood 77 per cent. 



Sapwood 110 per cent. 



The percentages are calculated to the dry weight of the wood. 



The differential distribution of moisture in Acer pseudoplatanusr 

 was fully investigated at Edinburgh (1). The investigation was car- 

 ried on during the dormant period of the tree, i.e., from October to 

 March. The matter^ was further studied at London during 1920, 

 and the results are given herein. The period of investigation was from: 

 February to September, that is, from the end of the winter to the- 

 beginning of the autumn. The trees selected for the main investiga- 

 tion were oaks {Quercus rol)ur) . In every case they were felled in 

 the morning and cross sections, two inches thick, were taken every 

 10 feet. These sections were at once wrapped in grease paper and 

 taken to the laboratory, where a strip one and a-half inches wide was 

 cut from the centre to the bark. These strips were then split into' 

 half-inch pieces, commencing at the centre. If there was an odd width 

 left at the sapwood end, this was considered as a half-inch, and is* 

 graphed accordingly. The small pieces were at once weighed and then 

 dried. The percentage of moisture is calculated to the dry weight of 

 wood. In some cases two strips were taken from the section, and 

 these are given on the graphs. In Fig. 1 is given a typical moisture 

 distribution in oak. The first tree was felled on March 2nd, 1920, 

 and the last tree on September 1st. All the trees were taken from 

 the same area and soil which was heavy clay. 



