but by the knowledge of this, even without the knowledge of the efficient cause, we have gained much light. Moreover, I am of opinion, as was said above, that the circulation of the blood has no properly efficient cause, but that the will is here as immediately active as in muscular movement where motives determine it by means of nerve conduction, so that here also the movement is called forth directly by the final cause; thus by the need of oxidation in the lungs, which here to a certain extent acts as a motive upon the blood, yet so that the mediation of knowledge is in this case wanting, because everything takes place in the interior of the organism. The so‐called metamorphosis of plants, a thought lightly thrown out by Kaspar Wolf, which, under this hyperbolic title, Goethe pompously and with solemn delivery expounds as his own production, belongs to the class of explanations of organic nature from the efficient cause; although ultimately he only says that nature does not in the case of every production begin from the beginning and create out of nothing, but as it were, writing on in the same style, adds on to what already exists, makes use of the earlier forms, developed, and raised to higher power, to carry its work further: just as it has done in the ascending series of animals entirely in accordance with the law: _Natura non facit saltus, et quod commodissimum in omnibus suis operationibus sequitur_ (_Arist. de incessu animalium, c. 2 et 8_). Indeed, to explain the blossom by pointing out in all its parts the form of the leaf seems to me almost the same as explaining the structure of a house by showing that all its parts, storeys, balconies, and garrets, are only composed of bricks and mere repetitions of the original unity of the brick. And not much better, though much more problematical, seems to me the explanation of the skull from vertebræ, although even here also it is a matter of course that the covering or case of the brain will not be absolutely different and entirely disparate from that of the spinal cord, of which it is the continuation and terminal knob, but will rather be a carrying out of the same kind of thing. This whole method of consideration belongs to the Homology of Richard Owen referred to above. On the other hand, it seems to me that the following explanation of the nature of the flower from its _final cause_, suggested by an Italian whose name has escaped me, is a far more satisfactory account to give. The end of the _corolla_ is—(1.) Protection of the pistil and the _stamina_; (2.) by means of it the purified saps are prepared, which are concentrated in the _pollen_ and _germs_; (3.) from the glands of its base the essential oil distils which, for the most part as a fragrant vapour, surrounding the anthers and pistil, protects them to a certain extent from the influence of the damp air. It is also one of the advantages of final causes that every