244 Prof. J. B. Farmer. On the Quantitative Differences in the 



explanation advanced for the dying back of the apex of the last-mentioned 

 tree, that the Sycamore is not likely to lose its apex. And, as a matter of 



Fig. 3. — Semi-diagrammatic sketch of the top of a young Sycamore tree. The figures in 

 brackets denote absolute volumes of water transmitted, those adjacent to them 

 denote the specific volumes, at the corresponding places. 



fact, it is very seldom that the leader in this species fails to maintain its 

 predominance until it finally becomes merged in the formation of the crown 

 of the maturing tree. 



It is evidently unsafe to draw conclusions as to the specific conductivity of 

 the branches of the adult tree from the behaviour of saplings or coppice- 

 shoots of the same species. Thus, the Oak and Ash are both low in respect 

 of the latter, but quite irregular, with very large values (from 70 to 120 or 

 more) for the adult shoots. This great range of conductivity is by no means 

 characteristic of all, or perhaps even of most, of the deciduous trees. Beech, 

 Hornbeam, Elm, Sycamore, to mention only a few, are fairly regular ; most 

 Willows, on the other hand, can hardly be represented by any average 

 number owing to their extensive fluctuation. It is just those species with 

 wide fluctuation, however, that are likely to prove most amenable to intelli- 

 gent treatment in respect of timber production, especially when it is desired 

 to encourage the development of qualities the structural background of which 

 is responsive to the influence of a particular environment. 



A somewhat extensive series of experiments has been made on fruit trees 



