240 Prof. J, B. Farmer. On the Quantitative Differences in the 



indicating specific (or relative) conductivity further emphasises the uniformity 

 of the secondary wood in this respect, when regarded from the point of view 

 of its composition per unit area. The Table (VI), which gives the results of 

 comparing two lengths from the main stems of 10 young sycamores, illustrates 

 the above points, and serves further to indicate the amount of variability that 

 may be expected to occur in such material. 



Table VI. — Ten Sycamore Sapling Trees with Sample Lengths (15 cm.) 

 tested at the Base and near the Apex respectively. 



No. 



Position. 



Age in 

 years. 



Absolute Tol. 

 in c.c. per i hour. 



Specific vol. 

 in c.c. per ^ hour. 



Average of 

 specific vol. 



9 

 10 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



basal 



apical 



4- 6 



5- 2 



8- 4 



9- 

 10 -8 

 10-2 



5-0 

 4-6 



4- 6 



5- 



4- 6 



5- 2 

 6 



4- 8 



6- 8 



5- 4 

 10 -8 

 10-2 



7- 2 

 7-2 



20 

 28 

 20 

 34 

 34 

 38 

 25 

 32 

 20 

 36 

 17 

 28 

 25 

 26 

 26 

 28 

 34 

 38 

 26 

 35 



I } 



•25 

 •40 

 •40 

 •65 

 •35 

 •55 

 •95 

 •10 

 •40 

 •05 



The general average of the specific volumes given in the last column = 28 •SI, and seven of the 

 ten sets of averages fall within ± 5 "5 of this number. 



The wood of the adult tree is always higher than that of the saplings, so 

 far as my observations have extended. This is borne out by comparing the 

 results given in Table VII with those contained in the two preceding Tables. 

 It will be seen that the numbers for this tree vary within small limits, 

 although the age and thickness of the twigs differed considerably. Corre- 

 sponding to this difference between the basal and upper parts of sapling trees, 

 a lowering of specific conductivity also distinguishes stool-shoots which spring 

 from coppiced stems. This is well seen in all the instances I have 

 investigated, e.g. Oak, Ash, Sycamore, Hazel, etc. 



The last-named plant, the Hazel, may be taken as typical of these, and 

 the wand-like rods that arise when the bush has been cut down very well 

 illustrate certain characteristically recurring features in this class of stems, 

 and in this they repeat the peculiarities of the young sapling trees as 



