We need only to recall to mind the exact parallelism which Alexander Agassiz and Neumayer have demonstrated to exist in the case of echinoderms, Huxley, Marsh, and others in the formation of the wings of birds, the pelvis of birds, or the hoofs of horses, in order to stamp this view as one that cannot be refuted. Nevertheless, those opposed to this view, as Carl Vogt, His, Heufen, and others, have not abandoned their position as a hopeless one, and in recent years have relied particularly upon those cases which Haeckel, and before him, Fritz Müller, characterised as a falsification (cenogenesis[16]) or a supplementary alteration and abbreviation of the natural process of development. “Nature is no falsifier,” these opponents proclaim with emphasis, and everything it does is correct and true, and “this false heart alone brings untruth and deceit into the true heaven,” they cry with Wallenstein. People who rely on verbal sophistries merely betray thereby their want of valid counter-arguments. A _mala fides_ on the part of nature can of course never be the subject of discussion among reasonable beings, but a deviation in the process of development of certain varieties from the typical path of the development of the remaining varieties of the species, is _felt_ as a falsification by every investigator who has thoroughly studied the regular processes, for the reason that it has a tendency to _obscure_ the original facts. Thus, for example, in the embryos of certain vertebrates the æsophagus is temporarily completely closed, as Balfour has observed in young sharks, Bles and Marshall in frogs; and this state of affairs may well be considered as a falsification, since an animate being with a closed æsophagus is a natural contradiction, which can never have existed and here happens as a supplementary and temporary process.