From these experiments it is clear that the apex of the radicle of the bean is sensitive to contact, and that it causes the upper part to bend away from the touching object.  But before giving a summary of the results, it will be convenient briefly to give a few other observations.  Bits of very thin glass and little squares [page 141] of common card were affixed with thick gum-water to the tips of the radicles of seven beans, as a preliminary trial.  Six of these were plainly acted on, and in two cases the radicles became coiled up into complete loops.  One radicle was curved into a semi-circle in so short a period as 6 h. 10 m.  The seventh radicle which was not affected was apparently sickly, as it became brown on the following day; so that it formed no real exception.  Some of these trials were made in the early spring during cold weather in a sitting-room, and others in a greenhouse, but the temperature was not recorded.  These six striking cases almost convinced us that the apex was sensitive, but of course we determined to make many more trials.  As we had noticed that the radicles grew much more quickly when subjected to considerable heat, and as we imagined that heat would increase their sensitiveness, vessels with germinating beans suspended in damp air were placed on a chimney-piece, where they were subjected during the greater part of the day to a temperature of between 69o and 72o F.; some, however, were placed in the hot-house where the temperature was rather higher.  Above two dozen beans were thus tried; and when a square of glass or card did not act, it was removed, and a fresh one affixed, this being often done thrice to the same radicle.  Therefore between five and six dozen trials were altogether made.  But there was moderately distinct deflection from the perpendicular and from the attached object in only one radicle out of this large number of cases.  In five other cases there was very slight and doubtful deflection.  We were astonished at this result, and concluded that we had made some inexplicable mistake in the first six experiments.  But before finally relinquishing the subject, we resolved to make one [page 142] other trial for it occurred to us that sensitiveness is easily affected by external conditions, and that radicles growing naturally in the earth in the early spring would not be subjected to a temperature nearly so high as 70o F. We therefore allowed the radicles of 12 beans to grow at a temperature of between 55o and 60o F. The result was that in every one of these cases (included in the above-described experiments) the radicle was deflected in the course of a few hours from the attached object.  All the above recorded successful trials, and some others presently to be given, were made in a sitting-room at the temperatures just specified.  It therefore appears that a temperature of about, or rather above, 70o F. destroys the sensitiveness of the radicles, either directly, or indirectly through abnormally accelerated growth; and this curious fact probably explains why Sachs, who expressly states that his beans were kept at a high temperature, failed to detect the sensitiveness of the apex of the radicle.