when, but not until, the conditions for further expansion shall have been fulfilled.
At the beginning of the nineteenth century the time was ripe for such an addition of new territory to the regions of Botany already occupied at that period. In England, at any rate, the work inaugurated by Ray and others had become overshadowed by the authority of Linnaeus, and even on the Continent the effective advance of the science was for various reasons almost stayed. It is true that in France the Jussieus had started advance on fruitful lines, and others like De Candolle were endeavouring to feel their way through the maze of dimly comprehended relationships, but their efforts were obscured by the growing and fatal facilities for piling up mere catalogues of plants without the clues necessary to direct their energies into more profitable channels. As regards the flowering plants, there was, it is true, a groping after a partially perceived natural system, but the lower ranks of the vegetable kingdom formed, so far as scientific purposes were concerned, a terra incognita, and the attempts to elucidate the morphology of these groups in the light of the angiosperms were, as we now can see clearly enough, plainly foredoomed to failure.
Facts were distorted and observations misinterpreted in ways that now seem to us almost to smack of sheer perversity, but we must not forget that the methods which in later years have proved so effective had not then been recognised; Hofmeister, with his marvellous genius, had not as yet arisen to shew the way through the maze of the lower forms.
But what does strike one as astonishing, or might do so if the circumstance were not still so common, is the evidence of the difficulty men experienced in really seeing things as they were, and of distinguishing the fundamentally important from the trivial or even irrelevant.
As always, what was needed was the man who could fix his gaze on facts, who would spare no pains to find out what was true, and thus succeed in discovering a sure base to serve as a vantage ground for further advance. Von Mohl was one of these, and earlier in the century there was the man, the subject of this lecture, who by his single-hearted search after truth, and
