There can, therefore, be no doubt that the
apex is highly sensitive to slight contact, and that the upper part of the
radicle bends away from the touching object.
Gossypium herbaceum: Sensitiveness of the apex of the Radicle.--Radicles
were experimented on in the same manner as before, but they proved
ill-fitted for our purpose, as they soon became unhealthy when suspended in
damp air. Of 38 radicles thus suspended, at temperatures varying from 66o
to 69o F., with squares of card attached to their tips, 9 were plainly and
7 slightly or even doubtfully deflected from the squares and from the
perpendicular; 22 not being affected. We thought that perhaps the above
temperature was not high enough, so 19 radicles with attached squares,
likewise suspended in damp air, were subjected to a temperature of from 74o
to 79o F., but not one of them was acted on, and they soon became
unhealthy. Lastly, 19 radicles were suspended in water at a temperature
from 70o to 75o F., with bits of glass or squares of the card attached to
their tips by means of Canada-balsam or asphalte, which adhered rather
better than shellac beneath the water.
Pages:
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295