. The theory of evolution in the light of facts. ehigher plants ^ which inhabited thesea we know nothing. Hence it happens that formationswhich are exclusively marine and,particularly for our present inquiry,very important stratifications—thepre-Cambrian, Cambrian, Silurian,Mussel Chalk, and others—only nowand then offer examples of sub-merged land plants. With regardto the flora we gather exact dataonly from those periods and regionswhere extensive areas of land weremarshy or, owing to great aerialhumidity, were covered with forests. Only under suchcircumstances were the conditions existent f
. The theory of evolution in the light of facts. ehigher plants ^ which inhabited thesea we know nothing. Hence it happens that formationswhich are exclusively marine and,particularly for our present inquiry,very important stratifications—thepre-Cambrian, Cambrian, Silurian,Mussel Chalk, and others—only nowand then offer examples of sub-merged land plants. With regardto the flora we gather exact dataonly from those periods and regionswhere extensive areas of land weremarshy or, owing to great aerialhumidity, were covered with forests. Only under suchcircumstances were the conditions existent for suchprocesses as led to the formation of the coal seams, inwhich we find entire generations of successive growths,^and these in the best condition. It must also beconsidered that none of the primeval plants have Higher plants we only accept temporarily in the sense of theirhigher systematic position, as they are recognized generally by botanists. ^ H. Potonie: Die Entstehung der Steinhohle und der Kaustobiolitheüberhäuft, Berlin, Fig. 10.—Sections , with bark; h, withbark removed show-ing bast; c, with bastremoved to truewood. {AfterGoihan.) KESULTS OF RESEARCH 51 practically survived as perfect examples or in theform of larger connected fragments, but mostly arefound as separated portions of one and the sameplant at different places—for instance the stem here,the leaves yonder,and the seeds andfruit somewhere is clear thatunder these circum-stances it is onlyin exceptional casesthat the properlyassociated parts canbe recognized assuch.^ To this must beadded that one andthe same plant occursin quite differentstates of preserva-tion, with or withoutbark (Fig. 10), stonekernels, pith tubes,etc., so that quitedifferent forms of growth may present themselvesand receive also different names. Fig. 10 will helpto a comprehension of this. It shows us three 1 Dr. W. Gothan: Entwicklung der Pflanzenwelt, Osterwieclc am Harz^1909, p. 6
Size: 1129px × 2213px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidtheoryofevol, bookyear1913
