Mesozoic floras of France being specially noteworthy among the able investigations which we owe to his ability and enthusiasm[23]. In Baron Ettingshausen[24] we have another representative of those students of ancient vegetation who have done so much towards establishing the science of fossil plants on a philosophical basis. As in other fields of Natural Science, so also in a marked degree in fossil botany, a new stimulus was given to scientific inquiry by the application of the microscope to palaeobotanical investigation. In 1828 Sprengel published a work entitled _Commentatio de Psarolithis, ligni fossilis genere_[25]; in which he dealt in some detail with the well-known silicified fern-stems of Palaeozoic age, from Saxony, basing his descriptions on the characteristics of anatomical structure revealed by microscopic examination. [Sidenote: THE INTERNAL STRUCTURE OF FOSSIL PLANTS.] In 1833 Henry Witham of Lartington brought out a work on _The Internal Structure of Fossil Vegetables_[26]; this book, following the much smaller and less important work by Sprengel, at once established palaeobotany on a firmer scientific basis, and formed the starting point for those more accurate methods of research, which have yielded such astonishing results in the hands of modern workers. In the introduction Witham writes, “My principal object in presenting this work to the public, is to impress upon geologists the advantage of attending more particularly to the intimate organization of fossil plants; and should I succeed in directing their efforts towards the elucidation of this obscure subject, I shall feel a degree of satisfaction which will amply repay my labour[27].” On another page he writes as follows,—“From investigations made by the most active and experienced botanical geologists, we find reason to conclude that the first appearance of an extensive vegetation occurred in the Carboniferous series; and from a recent examination of the mountain-limestone groups and coal-fields of Scotland, and the north of England, we learn that these early vegetable productions, so far from being simple in their structure, as had been supposed, are as complicated as the phanerogamic plants of the present day. This discovery necessarily tends to destroy the once favourite idea, that, from the oldest to the most recent strata, there has been a progressive development of vegetable and animal forms, from the simplest to the most complex[28].” Since Witham’s day we have learnt much as to the morphology of Palaeozoic plants, and can well understand the opinions to which he thus gives expression. It would be difficult to overrate the immense importance of this publication from the point of view of modern palaeobotany.