But suppose, even, that the _Acarus Crossii_ were admitted to be a real product of Galvanic action on the silicate of potash, and an undeniable instance of "a non-generative origin of life," how would the illustrative example accord with the author's general theory? It might afford a specimen of aboriginal production; but how would it fit in with his favorite doctrine of _a gradual and progressive advancement_ from the lower to the higher forms of organization? The _Acarus_, at first supposed to be a new and hitherto unknown creature, is now acknowledged to be one of a very familiar species,--a species which may have deposited its ova, and propagated its kind, since the commencement of the present order of things, and whose eggs might very well resist the action even of nitrate of copper, since the creature itself could live in that poisonous mixture. Moreover, it belongs, in point of organization, to one of the highest orders of organisms; not to the _radiata_, not to the _mollusca_, but to the highest type of the _articulata_, the nearest to the _vertebrata_. Had it been a monad,--a mere living cell,--which Galvanism evolved from the solution, and had this primary product developed itself afterwards in various forms, according to the ascending scale of a progressively improving organization, it might have accorded admirably with the twofold doctrine of spontaneous generation and transmutation of species; but, unfortunately, the first process is so perfect, in the present instance, as to leave little room for the second, and we are almost tempted to hope that perhaps the clumsy and troublesome expedient of a transmutation of species may yet be superseded by the discovery of some method,--we know not what,--whereby not only the _articulata_, but the _vertebrata_, and even Man himself, may be immediately produced by some new combination of Nature's elemental laws![47]