Tropaeolum majus: Sensitiveness of the apex of the Radicle to contact.--
Little squares of card were attached with shellac to one side of the tips
of 19 radicles, some of which were subjected to 78o F., and others to a
much lower temperature. Only 3 became plainly curved from the squares, 5
slightly, 4 doubtfully, and 7 not at all. These seeds were, as we believed,
old, so we procured a fresh lot, and now the results were widely different.
Twenty-three were tried in the same manner; five of the squares produced no
effect, but three of these cases were no real exceptions, for in two of
them the squares had slipped and were parallel to the apex, and in the
third the shellac was in excess and had spread equally all round the apex.
One radicle was deflected only slightly from the perpendicular and from the
card; whilst seventeen were plainly deflected. The angles in several of
these latter cases varied between 40o and 65o from the perpendicular; and
in two of them it amounted after 15 h. or 16 h. to about 90o. In one
instance a loop
[page 168]
was nearly completed in 16 h.
Pages:
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294