Rather large squares, though difficult
to affix, seemed more efficient than very small ones.
We were much more successful with caustic; but in our first trial, 15
radicles were too much cauterised, and only two became curved from the
blackened side; the others being either killed on one side, or blackened
equally all round. In our next trial the dried tips of 11 radicles were
touched momentarily with dry caustic, and after a few minutes were immersed
in water. The elongated marks thus caused were never black, only brown, and
about ? mm. in length, or even less. In 4 h. 30 m. after the cauterisation,
6 of them were plainly curved from the side with the brown mark, 4
slightly, and 1 not at all. The latter proved unhealthy, and never grew;
and the marks on 2 of the 4 slightly curved radicles were excessively
minute, one being distinguishable only with the aid of a lens. Of 10
control specimens tried in the same jars at the same time, not one was in
the least curved. In 8 h. 40 m. after the cauterisation, 5 of the radicles
out of the 10 (the one unhealthy one being omitted) were deflected at about
90o, and 3 at about 45o from the perpendicular and from the side bearing
the brown mark.
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