Water in Trees under Australian Conditions. 
9 1 
Dracaena Draco. 
Area of stomatal surface = 3*2356 sq. m. 
Stomata on both surfaces, most plentiful on upper surface along 
midrib. 
This plant was kept under observation from November 13 to 30 
inclusive, excepting 16th, 17th, and 24th. During this period the total 
loss amounted to 2,754*412 grams or an average of 172*15 per day. 
The average loss per hour per sq. m. = 11*7 grams. 
Average loss per hour per stoma = *00078 milligram. 
The following table shows a few of the individual results under as 
divergent conditions as possible :— 
Date and Temperature. 
Conditions. 
Loss per hour per sq. m. 
13. 11. ’07 
16*5° 
Shady, no wind 
i-8 grams 
14. 11. ’07 
2 4 
Clear, sun, no wind 
io-6 grams 
19. 11. ’07 
25 ° 
Clear, sun, slight wind 
13-2 grams 
per stoma = 
•00088 milligram 
21. 11. 07 
30 ° 
Cloudy, wind 
6-6 grams 
per stoma = 
•0004 milligram 
22. 11. 07 
33 ° 
Clear, sun, strong N. wind 
6-o grams 
(Stomata partly closed ?) 
23. 11. ’07 
30 ° 
Clear, sun and wind 
r 5-4 grams 
per stoma = 
-ooi milligram 
25. 11. 07 
30 ° 
Cloudy, strong N. wind 
17.6 grams 
per stoma = 
.00117 miligram 
26. 11. ’07 
19 * 5 ° 
Cloudy, S. wind 
6-6 grams 
20. 11. ’07 
20-5° 
Clear sky, slight wind 
(plant in shade) 
4-4 grams 
per stoma = -00029 milligram 
Apparently in this case with a hot dry north wind, transpiration attains 
a maximum at or near 30° C. of 17 to 18 grams per hour per sq. metre. If 
the temperature rises beyond this the stomata begin to close and the rate 
of transpiration falls. 
The Rate of Ascent of Sap in Eucalyptus Trees. 
A few orientating experiments were performed with some trees of 
Acacia mollissima which happened to be available. The best method is to 
cut the trees with a very sharp axe, keeping the cut surface under a jet of 
water. The cut end is then placed in a bucket of filtered water for a few 
minutes, and then rapidly transferred to a vessel containing a measured 
