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LOCK : THE GROWTH OF 
marked effect resulting from changes in the humidity of the 
air. His fig. IV. and Table III. shows a very marked 
parallelism to exist between the curve of growth and that 
constructed from readings of the psychrometer. 
The following are Reinke’s principal conclusions:— 
(a) Generally speaking the change in volume is proportional 
to the relative moisture of the air. 
( b ) With a high degr.ee of moisture an energetic increase 
in volume of the stem takes place. With à marked reduction 
of moisture there occur, not only a smaller increase, but an 
actual and marked shrinking of the stem volume. 
(c) Not infrequently the curve of growth sinks below zero 
when moisture has sunk only a few degrees from a high point 
on the psychrometric scale. If the moisture now remains 
constant at this lower point, growth finally begins once more. 
In this case the plant becomes acclimatized, as Reinke 
phrases it, to a low degree of moisture which was at first 
harmful. 
These changes are connected by the author with the 
evaporation of water from the leaves. 
The whole of this effect ought perhaps not to be attributed 
to changes of growth, for Kraus has shown"" that in the case 
of certain plants, in branches not actually growing, there is 
a regular periodic interchange of water between the wood 
and the cortex accompanied by a change in the total 
diameter of the stem. 
The facts with regard to the elongation of bamboo 
internodes agree closely with these results of Reinke’s, 
except that in the case of the former the contraction which 
was sometimes observed to take place when the air was dry 
was never very large. 
To explain why the internodes examined by him showed 
no such changes in the course of their elongation, Reinke 
suggested that these were less easily affected because of the 
* Gregor Kraus, Ueber die Wasservertheilung in der Pflanze, Part I.. 
Festschrift der Katurforsch. Ges. zu Halle, 1879. 
