Even within twenty-four
hours the sugar has slightly diminished in proportion in the fluid.
Whether or not this little note throws a single ray of light on the much
debated question of the cause of the rise of sap in plants I must leave
to botanists to decide. I cannot hope that it does, for Julius Sachs,
than whom no one appears to have more carefully considered the subject,
says, at page 677 of the recently published English translation of his
textbook of botany, that "although the movements of water in plants have
been copiously investigated and discussed for nearly two hundred years,
it is nevertheless still impossible to give a satisfactory and deductive
account of the mode of operation of these movements in detail." As
a chemist and physicist myself, knowing something about capillary
attraction, exosmose, endosmose, atmospheric pressure, and gravitation
generally, and the movements caused by chemical attraction, I am afraid
I must concur in the opinion that we do not yet know the real ultimate
cause or causes of the rise of sap in plants.
Ashlands, Watford, Herts.
* * * * *
THE CROW.
[Footnote: Abstract of a recent discussion before the Connecticut State
Board of Agriculture.
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