Passing on to the more special problems of botanical enquiry, Schleiden next dwells on the history of development as the foundation of all insight into morphology, though he overshot the mark when he rejected as unfruitful the simple comparative method, which had produced considerable results in the hands of De Candolle, and was virtually the fruitful element in the doctrine of phyllotaxis of Schimper and Braun. Still he took an active part himself in the study of development in plants, and gave special prominence to embryology; he also discussed the doctrine of metamorphosis from the point of view of the history of development, and pointed to Caspar Friedrich Wolff’s treatment of that subject as much clearer than that which had been introduced by Goethe. Finally, Schleiden’s mode of dealing with the natural system must be reckoned among the good services which he rendered to method; not because his classification of the vegetable kingdom presents any specially interesting features or brought to light any new affinities, but because we see an attempt made for the first time to give detailed characters drawn from morphology and the history of development to the primary divisions, and because by this means the positive and distinct nature of the Cryptogams was from the first clearly brought out. The old way of treating morphology, as though there were only Phanerogams in the world, and then having recourse to unmeaning negatives in dealing with the Cryptogams, was thus set aside, much to the profit of the immediate future, which directed its attention specially to the Cryptogams.