6S 



SCIENCE-GOSSIP. 



[Mauch 1, 1865. 



GEOLOGY. 



The Study of the Past IIisTorvY of Existing 

 Species of Plants. — In a recent paper on the "Ori- 

 gin of the British Plora," it was suggested, in proof of 

 its probable antiquity, tliat ligneous as well as herba- 

 ceous plants may have been preceded by numerous 

 generations. If we confine our reinarks to the 

 existing species of oak, elm, maple, pine, yew, and 

 cedar, some of which wc knoAv to have lived for 

 Iiundrcds of years, and, in tlie case of yew and 

 cedar, from fifteen liundred to two tliousaud years— 

 since inductive science is not able to make us 

 understand extra-natural phenomena— we can only 

 determine tlie probable number of generations 

 wliich have preceded the birth of these monarclis 

 of the forest, or their botanical dynasty, by an 

 appeal to the testimony of the rocks. We know 

 from the evidence of the rocks, that existing vege- 

 tation is only a continuation, throngli _ numerous 

 geological changes, of an anterior vegetation. How 

 long, then, have the existing species of oak, ehn, 

 maple, pine,_yew, and cedar, been in existence? at 

 what geologjical epoch were they introduced ? and 

 to what extinct species is their ancestry traceable? 

 An attempt to answer these questions has yet to 

 be made. Our most eminent living geologists— 

 Ijj^ell and Prestwich — will acknowledge as much. 

 Very little has yet been done in quaternary geology 

 by botanists, and what has been done seems to ns 

 to be most unsatisfactory. The_ question as to the 

 successive epochs at which existing species have 

 made their appearance can only be determined by a 

 careful study of the botanical remains found in, com- 

 paratively speaking, recent geological formations ; 

 and as leaves appear to be the most common forms 

 in which these remains are found, in many instances 

 tlie nervation being most beautifully preserved, it 

 followts that the careful study of the nervation of 

 the leaves of existing species is a very suitable pre- 

 paration for these researches. As a means of en- 

 abling us to study the ramifications of the nerves 

 in the leaf, the process of nature-printing offers us 

 most invaluable aid. When we consider how 

 exceedingly polymoi-phous the leaves are on most 

 plants; how leaves, in the neighbourhood of the 

 flower, lose their lobes, teeth, and other incisions, 

 and. take an entire edge, or lose their petiole and 

 become sessile, sliding imperceptibly nito bracts, 

 aud_ then intp the sepals of the calyx, it must be 

 obvious that in the case of vegetable remains, where 

 leaves only are found, in determining a fossil plant 

 from its leaf, we must fall back on characters more 

 constant, and therefore more reliable. These cha- 

 racters are furnished by the nervation of the leaves. 

 Unhappily, wc have not at present any Avork in the 

 English language in which a classification of tlic 

 various types of leaves has been effected, founded 

 on characters taken from their nervation. The only 

 work to which we can refer the reader is an exceed- 

 ingly expensive one, published by the Austrian 

 government. 'In this work the Austrian flora has 

 been copied by the nature-printing process. A 

 separate work has also been published on the ner- 

 vation of leaves. There is nothing to prevent such 

 English botanists, whose neighbourhoods aiford the 

 necessary facilities, from working in this novel and 

 deeply.intercsting fleld. We want a list of our living 

 plants, and the relative ages of the geological form- 

 ations in which they are found. The most recent 

 beds arc the most important, as l)earing directly 

 upon this question, as to the anti(|uity of the exist- 

 ing species of ligneous plants. We most earnestly 



call the attention of botanists to this subject, re- 

 minding theni that, Aviierever a plant is found, 

 whether on the earth's surface or in its interior, it 

 is legitimate botanizing territory. It is certain that 

 nature is now preserving in modern lacustrine, 

 fiuviatile, and estuarine deposits, specimens of 

 existing species; we know that she has done so at 

 former epochs; it is, therefore, apparent that it is 

 only in these modern formations that the lost 

 links will be discovered vvhich unite the present 

 with the former plant creations. H. C. 



The Order of Succession in the I>Rirx- 

 BKDs OF THE IsLAND OF Arran. — At a meeting of 

 the Geological Society (Jan. 25), Dr. J. Bryce read a 

 paper on this subject. " In a paper read last year 

 before the Iloyal Society of Edinburgh, the Kev. 

 II. B. Watson described all tliese beds as bouldcr- 

 clay, and did not assign the shells which he had 

 discovered in them to any particular part of the 

 deposit. Dr. Bryce dissented from this view, and 

 in this paper pointed out the various causes of error 

 likely to mislead an observer in examining such 

 accumulations. He then described the various 

 sections of the deposits, and showed that the lowest 

 bed is a hard, tough, unstratiiied clay, full of striated, 

 smoothed, and polislied stones of all sizes, but 

 totidly devoid of fossils, and that it is, in feet, the true 

 old boulder-clay of the geologists of the west of 

 Scotland. The shells are entirely confined to a bed 

 of clay of open texture, containing a few small 

 stones ; it rests immediately on the boulder-clay as 

 above defined, and is succeeded by various drift- 

 beds, eor.sistlng of seams of clay and sand inter- 

 mingled, containing stones that are rarely striated, 

 and without shells. Dr. Bryce then discussed the 

 ]n-obable origin of these drifts, and the amount of 

 depression which the land had sustained before the 

 shell-bed was deposited over the boulder-clay, which 

 he considered to have been formed by land-ice 

 emanating from central snow-fields, and covering 

 the whole surface of the country." — The Reader. 



The Occurrence of Beds in the West of 

 Scotland in the Position of the English 

 Crag. — Dr. Bryce also read a paper on this subject at 

 the same time and place as the last. "In conse- 

 quence of the results arrived at from the investiga- 

 tion of the drift-beds of Arran, Dr. ]5ryee determined 

 to examine all the recorded cases of fossils occurring 

 in the boidder-clay, the Chapel Hall case having, 

 however, been already undertaken by the Rev. H. 

 W. Crosskey. Tlie most celebrated case is that of 

 the occurrence of elephant-remains at Kilmaurs, 

 near Kilmarnock, in Ayrshire ; and the author 

 showed, from a section of the quarry exposed for 

 the purpose by Mr. Turner, of Dean Castle, which 

 corresponded exactly with one already furnished to 

 him by an aged quarryman, that the elephant-remains, 

 the reindeer's horn, and the shells, all occurred in 

 beds below the bouklcr-clay, and not hi that 

 deposit, as has always been stated. The same 

 conclusion was arrived at respecting the occur- 

 rence of elephant-remains at Airdrie and Bishop- 

 briggs, and of reindeer's horn with shells at 

 Croftamie ; and the author concluded by discussing 

 the question whether the fossils belong to the 

 Upper Crag period, or merely indicate a downward 

 extension of the iVrctie fauna which characterizes 

 the beds directly above the bouklcr-clay, as described 

 in the last paper." 



