10 
Transactions of the Royal Society of South Africa. 
made of both transpiration and conduction, the average conductivity then 
obtained being 7 9. In the later set of experiments, however, the range of 
values was greater, the lowest being 5*6 and the highest 9*3. The average 
conductivity obtained from all the experiments was 7'5. 
In the case of the Silver Tree, nine experiments in July gave values 
ranging from 130 to 26 0, the average being 20'8. The January experi- 
ments gave lower values ranging from 100 to 24 6 with an average of 16*2. 
The average for all the experiments was 17*8. 
These results are tabulated in Table I, in which some of Farmer's 
figures are included for comparison. 
Table I. — Measurements of Conductivity. 
Oak. 
Pinus 
pinaster. 
Finns 
sylvestris. 
Range . . . 
Conductivity (average) (186 cm. water) 
Specific conductivity (30 cm. mercury) : 
Aitken ...... 
Farmer ...... 
18-9-1078 
46-6 
1025 
75 ± 15 
5-6-9-3 
7'5 
165 
13 ±2 
Leucadendron 
argenteu m. 
Euonymus 
japonica 
(evergreen). 
Euonymus 
europaeus 
(deciduous). 
Conductivity (average) (186 cm. water) 
Specific conductivity (30 cm. mercury) : 
Aitken 
Farmer ...... 
10-0-26-0 
17-8 
392 
121 
40 2 
The present writer's figures show clearly that the wood of the deciduous 
Oak has a much higher conductivity than has that of the Pine or Silver Tree, 
and it also gives a larger range of values. This is in accordance with 
Farmer's main conclusion already quoted. 
Comparing the two sets of values for the specific conductivity, a con- 
siderable divergence will be noticed in the case of the Oak. This is probably 
due to the small number of experiments performed by the present writer, 
for although the average is so much higher, the range of individual values 
is similar. The specific conductivity of Pinus pinaster is only a little 
greater than that of the species investigated by Farmer. For an evergreen 
tree Leucadendron argenteum has a remarkably high specific conductivity, 
its value being very nearly equal to that of the deciduous Euonymus 
japonica. 
