Transcriber Note: This correction has been applied. Here is the original text with the changes indicated:—
One filmy species of Todea is represented in the British flora by Todea radicans in the Killarney district of Ireland; but tThe maximum development of the genus is in New Zealand.
[CHAPTER I]
INTRODUCTORY: THE LONGEVITY OF TREES, ETC.
'Believe me who have tried. Thou wilt find something more in woods than in books. Trees and rocks will teach what thou canst not hear from a master.' St Bernard.
The recent publication in the daily press of instances of human longevity under the heading 'Links with the Past' prompted a comparison between the length of time represented by the duration of a tree and the lifetime of a human being. The comparison of single lives suggested the further step of contrasting the antiquity of the oldest family-histories with the remoteness of the period to which it is possible to trace the ancestry of existing members of the plant kingdom.
My primary object in these pages is not to deal with familiar cases of longevity in trees, but to consider in the first place some of the problems connected with the origin of the present British flora, and then to describe a few examples of different types of plants whose ancestors flourished during periods of the earth's history long ages before the advent of the human race.
In dealing with plants of former ages we are confronted with the difficulty of forming an adequate conception of the length of time embraced by geological periods in comparison with the duration of the historic era. Some of the 'Selections from the Greek Papyri' recently edited by Dr Milligan (Cambridge 1910) refer to common-place events in terms familiar to us in modern letters: we forget the interval of 2000 years which has elapsed since they were written. Similarly, the close agreement between existing plants and species which lived in remote epochs speaks of continuity through the ages, and bridges across an extent of time too great to be expressed by ordinary standards of measurement. Terms of years when extended beyond the limits to which our minds are accustomed cease to have any definite meaning. While there is a certain academic interest in discussions as to the age of the earth as expressed in years, we are utterly unable to realise the significance of the chronology employed. After speaking of the futility of attempting to introduce chronological precision into periods so recent as those which come into the purview of archaeologists, Mr Rice Holmes suggests a method better adapted to our powers. He says—'Ascend the hill on which stands Dover Castle, and gaze upon Cape Grisnez, let the waters beneath you disappear; across the chalk that once spanned the channel like a bridge men walked from the white cliff that marks the horizon to where you stand. No arithmetical chronology can spur the imagination to flights like these([1]).' On the other hand, the use in some country districts in Britain of spindles almost identical with instruments used in spinning by the ancient Egyptians, and similar survivals described by the author of a book entitled The Past in the Present([2]), bring within the range of our vision an early phase of the historic era. The rude implements still fashioned by the flint-knappers of Brandon in Suffolk connect the present with the Palaeolithic age. Measured from the standpoint of historic reckoning, survivals from prehistoric days appeal to us as persistent types which have remained unchanged in a constantly changing world.