in that case of course such Orchideae as have no chlorophyll, the Orobancheae, Cuscuta, Rafflesia, etc., would form one class with the Fungi, and all other plants the other. It is very important for the existence of a plant whether its organisation is adapted to its growing in water, or on dry land, or underground, and if we took Lindley at his word, he would be obliged to bring the Algae, Rhizocarps, Vallisnerias, water Ranunculuses, Lemna, etc., into one group. It is very important for the existence of a plant whether it grows upright of itself, or climbs upwards by the aid of tendrils or of a twining stem or otherwise, and accordingly we might on Lindley’s principle collect certain ferns, the vine, the passion-flower, many of the pea kind, etc., into one order. It is obvious that Lindley’s main axiom of systematic botany appears in this way utterly unreasonable; yet by this principle he judges of the systematic value of anatomical characters, those of the embryo and endosperm, of the corolla and the stamens, everywhere laying stress on their physiological importance, which in these parts has really little systematic value. This mode of proceeding on the part of Lindley, compared with his own system, which with all its grave faults is still always a morphologically natural system, proves that like many other systematists, he did not literally and habitually follow the rules he himself laid down, for if he had, something very different from a natural system must have been the result. The success which was really obtained in the determination of affinities was due chiefly to a correctness of feeling, formed and continually being perfected by constant consideration of the forms of plants. It was still therefore virtually the same association of ideas as in de l’Obel and Bauhin, operating to a great extent unconsciously, by which natural affinities were by degrees brought to light; and men like Lindley, of pre-eminent importance as systematists, were, as the above examples show, never clear about the very rules by which they worked. And yet in this way the natural system was greatly advanced in the space of fifty years. The number of affinities actually recognised increased with wonderful rapidity, as appears from a comparison of the systems of Bartling, Endlicher, Brongniart, and Lindley, with those of De Candolle and Jussieu. Nothing shows the value of the systems thus produced before 1850 as classifications of the vegetable kingdom more forcibly than the fact that a clear and methodical thinker like Darwin was able to draw from them the chief supports of the theory of descent. For it is quite certain that Darwin has not framed his theory in opposition to morphology and system, and drawn it from any hitherto unknown principles; on the contrary, he has deduced his most important and most incontestable propositions directly from the facts of morphology and of the natural system, as it had been developed up to his time.