the Branches in Shrubs and Trees. 
637 
In summary the results showed : — 
1. - The seasonal movement observed the year before is confirmed, 
and is shown to consist in a gradual inward movement from leaf-fail until 
March, when an outward movement begins. 
2. There exists in addition to this seasonal movement a secondary 
movement, which is closely dependent upon temperature (as shown by the 
typical examples on Fig. 55), a higher temperature resulting in an outward, 
and a lower in an inward movement, and this movement is appreciable 
within a single day and night. 
3. There are sundry irregularities in the movements, and apparently 
a greater movement in north and east than in south and west branches. 
The close correlation between the secondary movement and changes 
of temperature thus demonstrated is interesting and important, and it is 
close enough to warrant the application to the movement of the term 
thermometric. Since the minor movement is of this character, the question 
at once naturally arises whether the seasonal movement may not be of 
the same character, that is, whether the seasonal movement may not be 
simply a thermometric movement of huge amplitude. This point will be 
discussed below. 
The results in relation to the respective amounts of movement in the 
different branches were not satisfactory. In general they showed more 
movement in the north and east branches, but with so many exceptions 
and irregularities that no conclusions can be drawn from them, the more 
especially as no precautions were taken to select branches of the same 
length and distance from the central post. Furthermore, both Miss Persons 
and myself were influenced by a belief that the north and east branches 
did move the most, and hence doubtless something of a personal equation, 
or rather an equation of prejudice, in this direction became incorporated 
into the results. 
The reality of the seasonal movement, and the correlation of the 
secondary movement with temperature changes, being thus made apparent, 
it remained to ascertain their precise physical basis, a subject both of much 
interest in itself and also important for the light it might throw upon the 
significance of the movement to the plant. Reviewing the facts so far 
observed, it seemed plain that the relation of the two movements may be 
either one of these two : — (a) they may be due to the same causes, the 
secondary inward-and-outward fluctuations being the result of temporary 
intensifications and weakenings of the factors (connected with temperature) 
producing the seasonal movement ; or (b) they may be due to different 
causes (or at least to a difference in the mode of operation of the same 
causes), the secondary fluctuations being temporary movements due to 
special causes, either out from, or in from, the line of general seasonal move- 
ment. The facts at our command seemed at first to point to the latter 
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