became curved towards the much blackened side, owing to the continued
growth of the opposite side. This difference in the results is interesting,
for it shows that too strong an irritant does not induce any transmitted
effect, and does not cause the adjoining, upper and growing part of the
radicle to bend. We have analogous cases with Drosera, for a strong
solution of carbonate of ammonia when absorbed by the glands, or too great
heat suddenly applied to them, or crushing them, does not cause the basal
part of the tentacles to bend, whilst a weak solution of the carbonate, or
a moderate heat, or slight pressure always induced such bending. Similar
results were observed with Dionaea and Pinguicula.
The effect of cutting off with a razor a thin slice from one side of the
conical apex of 14 young and short radicles was next tried. Six of them
after being operated on were suspended in damp air; the tips of the other
eight, similarly suspended, were allowed to enter water at a temperature of
about 65o F. It was recorded in each case which side of the apex had been
sliced off, and when they were afterwards examined the direction of the
curvature was noted, before the record was consulted.
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