. Beihefte zum botanischen Centralblatt. Plants. Bums, Regeueratioii and its relation to trauniatioijiöin. 163 No. of Time in hori- Time in vor- Time in reversed Time on klino- Ilesults when re- seeds. zontal position tical ijosition liorizontal position. stat in casts. Ihr. llir. in casts. in casts. 20 10 hrs. 15 15 hrs. 20 15 hrs. 37 5 hrs. 7 hrs. 10 1 hrs. 2hrs. 10 10 min. 6hr: Ihr. moved froni casts and rovolved on klinostat. Kesponded to first Stimulus. ditto. Responded to tlie second Stimulus. Grew straight. ditto. 9 grew straight 1 developed the curve. A study of this table shows that r
. Beihefte zum botanischen Centralblatt. Plants. Bums, Regeueratioii and its relation to trauniatioijiöin. 163 No. of Time in hori- Time in vor- Time in reversed Time on klino- Ilesults when re- seeds. zontal position tical ijosition liorizontal position. stat in casts. Ihr. llir. in casts. in casts. 20 10 hrs. 15 15 hrs. 20 15 hrs. 37 5 hrs. 7 hrs. 10 1 hrs. 2hrs. 10 10 min. 6hr: Ihr. moved froni casts and rovolved on klinostat. Kesponded to first Stimulus. ditto. Responded to tlie second Stimulus. Grew straight. ditto. 9 grew straight 1 developed the curve. A study of this table shows that roots are able to hold the influence of a geotropic stimidus for a very short time only. It would be interesting to determine the exact length of tinie but from the standpoint of this paper it is not essential. Auatomical studies. In the foregoing experiments it has been noted that the roots tiu'iied down in answer to gravity after a eertain length of time. Roots were killed and sectioned longitudinally to study their structui'e at the time when this change took place. Those roots were selected on which the brov»-n mass of dead tissue still remained. This usually dropped off during the process of im- bedding but by using a large part of the root it was not hard to get sections through that jDai't of the root which had been wounded. A study of these sections shoAved no trace of the wound. The process of regeneration was completed. A series of sections was now made from roots which had been wounded and which still showed a marked traumatropic cui*ve. Figure 4 shows part of the longitudinal section of a root which was kiUed 48 hours after wounding. At the time it was killed it was o-rowin«: at an angle of 90 degrees. The ligm-e shows that the wound has not been regenerated l)ut that process is still going Fiff. 4:. Disciissioii and couclusioiis. A review of the facts obtained by the experimental work cited in the preceding pagos show that the two phenomena. re- generation a
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