theory of original types. The assumption that every natural group represents an idea was here quite out of place; the notion entertained up to that time of what was really meant by the natural system had to be entirely altered; it could as little pass for a body of Platonic ideas as for a mere framework of conceptions. But the effect of the work was great in respect to the system also; the Cryptogams were now the most important objects in the study of morphology; the Muscineae were the standard by which the lower Cryptogams must be tried, the Ferns were the measure for the Phanerogams. Embryology was the thread which guided the observer through the labyrinth of comparative and genetic morphology; metamorphosis now received its true meaning, when every organ could be referred back to its parent-form, the staminal and carpellary leaves of the Phanerogams, for example, to the spore-bearing leaves of the Vascular Cryptogams. That which Häckel, after the appearance of Darwin's book, called the phylogenetic method, Hofmeister had long before actually carried out, and with magnificent success. When Darwin's theory was given to the world eight years after Hofmeister's investigations, the relations of affinity between the great divisions of the vegetable kingdom were so well established and so patent, that the theory of descent had only to accept what genetic morphology had actually brought to view.
So gorgeous a picture as Hofmeister had designed of the genetic connection of the vegetable kingdom, except the Thallophytes, could not possibly be completely perfect and correct in all its separate features; there were still many gaps to fill up and particular observations to correct. Hofmeister himself continued his labours; the remarkable genera Isoetes and Botrychium were in the following years more carefully studied by himself, the fertilisation and embryology of the Equisetaceae by himself and Milde, and those of Ophioglossum by Mettenius, and all were fitted into their place in the system. To the present day it is always a profitable
