366 SKETCH OF PALEOBOTANY. 



formity over the whole globe as we go back in time. The fact that 

 even the Tertiary floras of the most remote regions of the world possess 

 a striking resemblance among one another, wholly unknown among ex- 

 isting floras, has only just now fairly revealed itself to science, and found 

 its striking confirmation in the very recent work ^ of Baron von Et- 

 tingshausen on the Tertiary Flora of Australia. This uniform char- 

 acter of the fossil floras of different epochs, combined with their varia- 

 tion from one epoch to another, lends hope to paleobotany and leads to 

 the belief that when we shall have learned with precision the true char- 

 acteristics of each flora — learned to distinguish the accidental f^om the 

 essential, and geographic from chronologic characteristics — we shall be 

 in a condition to apply the data at hand to the explanation and eluci- 

 dation of the geologic and biologic history of the earth. 



While it is upon the defectiveness of the geologic record, so far as 

 plants help to make it, that the chief stress is usually laid, still, could 

 this record be so edited that it could be made to convey its full mean- 

 ing it would probably be found that it is really more complete than 

 the biologic record ; in other words, the knowledge we have of fossil 

 plants would go further in explaining geologic succession and deter- 

 mining questions of age than it can be made to do in explaining the 

 mode of development, distribution, and differentiation of plant forms 

 on the earth's suface. On the subject of geographical distribution, with 

 which are inevitably bound up many questions of origin, variation, and 

 descent, much has already been written. De CandoUe. Hooker, Gray, 

 Grisebach, Bttingshausen, Heer, and Engler have at diflerent times and 

 iu numerous ways succeeded in building up a body of valuable Uterature 

 relating to phytogeography. Since, however, this concerns itself prin- 

 cipally with explaining the origin of existing floras, chiefly dicotyledon- 

 ous, it cannot reach back to the primary and doubtless ever insoluble 

 problems of the differentiation of the great types of vegetation that have 

 successively dominated the plant life of the globe through past geologic 

 ages. Yet, however hopeless the task when the idea of complete solu- 

 tion is considered, it is nevertheless these very questions which are con- 

 stantly pressing upon the thoughtful student, and he cannot suppress 

 them if he will , or cease to recognize that they are legitimate, and that 

 every, even the least, approach towards their solution is so much clear 

 gain to science. 



TI.-INTEEDEPBNDENCE OF BOTANY AND PALEOBOT 



ANY. 



It is only quite recently that botanists have begun to turn their atten- 

 tion to questions of this kind. The overthrow of the doctrine of fixity 

 ©f species opened the door to such considerations, rendering them legiti- 



iiBeitrage zur Kenntniss der Tertiarflora Australiens. Vou C. von Ettingshansen. 

 Denksobr. d. k. k. Akad. d. Wissensch., Bd. XLVII, Wien, 1883. 



