172 BULLETIN 1059, U. S. DEPARTMENT OE AGRICULTURE. 
writers know of no single method or basic method of following these 
reactions which promises more than the method of following the 
plant's condition by frequent observations on the osmotic pressure 
or sap density. In the case of trees, the termini should of course be 
studied, but it is probable that valuable supplemental data can be 
obtained at one or two points along the stem and on side branches. 
Through this method, with any individual tree, it may be possible to 
depict the sudden influx of sap in the spring, which precedes the first 
growth; the gradual increase in carbohydrates as the new tissues- 
continue to function, and temporary changes due to water supply 
and water loss. Possibly the end point of the season's photo-synthetic 
activity may be found, if there is any: the same method will show 
the changes which the tree undergoes through the winter. In addi- 
tion to osmotic pressures, the starch content of leaves should be 
examined from time to time. It is self-evident that these data can 
only be interpreted when correlated with observations on both the 
soil and atmospheric conditions. 
A method which would show the rate at which the tree is being 
supplied with water would be a valuable adjunct to the above; but 
no attempt of this nature is known, beyond transpiration studies. It 
is possible, however, that a means may be devised by which this rate 
may be directly determined. There is room for a great deal of de- 
velopment in these lines. 
FIELD OBSERVATIONS, PHOTOGRAPHS, AND MAPS. 
The " Daily Observations " form in the series for climatological 
studies, intended for field observations, is thought to be adapted to 
universal use. It is of a size to fit Forest Service loose-leaf notebooks, 
6$ by 4 inches. It contains lines for all factors on which regular ob- 
servations are likely to be taken. It has five vertical columns, which 
may be used for five stations visited consecutively on the same day, or 
for a single station visited for five consecutive observations. In the 
first instance the numbers of the stations would be stamped at the 
heads of the several columns and the date^would be stamped at the 
bottom. In the second instance the days of the month would be 
stamped at the heads of the several columns and the month and year 
at the foot of the form. In either case the exact time of observation 
should be entered in the second line of each column. Since observa- 
tions at completely equipped stations may take from 10 to 20 minutes, 
the time entered for such stations should be, as nearly as possible, the 
time of reading current temperature and anemometer, these condi- 
tions being subject to considerable changes in a few minutes. 
Each point chosen as a site for ecological study should, in addition to 
a complete description 23 of the features which may influence soil qual- 
23 The " Description " form is suggestive. 
