To learn what were Meyen’s independent contributions to the advance of phytotomy, we must turn to his ‘Phytotomie’ of 1830; for in his later works and especially in the ‘Neues System der Physiologie’ of 1837 he was able to avail himself of von Mohl’s earliest and searching investigations; these necessarily influenced his views, though he always assumed the character of a rival and opponent of von Mohl, and treated not only Treviranus and Link, but even Kieser and men of his stamp, as entitled to equal rank with him. And as in his later writings he was reluctant to acknowledge von Mohl’s services to science and overlooked their fundamental importance, so in his earlier work in 1830 he often appears as an assailant of Moldenhawer and tries to set up Link’s authority against him; we find to our astonishment in the first volume of the ‘Neues System’ a dedication to Link as the ‘founder of German vegetable physiology.’ The position of a scientific man in relation to his science as a whole is certainly most simply and clearly defined by his judgment on the merits of his contemporaries and predecessors, and we may conclude from what has now been said that Meyen moved within the circle of ideas of the Göttingen prize-essays, and did not clearly see the importance of the points of view opened by Moldenhawer and von Mohl; though it must always be allowed that Meyen working independently far outstripped Link on his own path. If it was our purpose to write a biography of Meyen, we should have to go through his works, and show the steps by which his views arrived at clearness and precision; it is sufficient in this history to show what was peculiar and original in his general conception of the problems of phytotomy. This appears most plainly in the ‘Phytotomie’ of 1830; and we may base our historical survey on that work because its views are in the main those of the first volume of the ‘Neues System’ which appeared seven years later, and still more because a detailed examination of the later publication would involve us in a lengthy discussion on Meyen’s scientific relation to von Mohl. It is less important in this place to give an estimate of Meyen’s character as a man of science than to show, how in the year 1830, when Mohl was beginning to apply himself to phytotomy but as yet exercised no important influence on opinion, views on the structure of plants were formed by one who gave himself up to its study with decided ability and great zeal; in this way we shall gain a standard by which to judge of the advance made chiefly by von Mohl and in part by Mirbel during the succeeding ten years. In judging of Meyen’s book, we must not forget that it was written when he was only twenty-five or twenty-six years old, and that it is under any view of it a remarkable performance for so young a man.