fore-ordaining mind, which knows how to construct an electric battery by thus transforming muscular tissue into electric tissue, and is now actually in process of constructing such an apparatus for the prospective benefit of future creatures. Should it be suggested that possibly the electric organ of the skate may be in process of degeneration, and therefore that it is now the practically functionless remnant of an organ which in the ancestors of the skate was of larger size and functional use--against so obvious a suggestion there lie the whole results of Professor Ewart's investigations, which go to indicate that the organ is here not in a stage of degeneration, but of evolution. For instance, in _Raia radiata_, it does not begin to be formed out of the muscular tissue until some time after the animal has left the egg-capsule, and assumed all the normal proportions (though not yet the size) of the adult creature. The organ, therefore, is one of the very latest to appear in the ontogeny of _R. radiata_; and, moreover, it does not attain its full _development_ (i. e. not merely _growth_, but transforming of muscular fibres into electrical elements) till the fish attains maturity. Read in the light of embryology, these facts prove, (1) that the electric organ of _R. radiata_ must be one of the very latest products of the animal's phylogeny; and, (2) that as yet, at all events, it has not begun to degenerate. But, if not, it must either be at a stand-still, or it must be in course of further evolution; and, whichever of these alternatives we adopt, the difficulty of accounting for its present condition remains. In this connexion also it is worth while to remark that the electric organ, even after it has attained its full _development_, continues its _growth_ with the growth of the fish, and this in a much higher ratio, either than the tail alone, or the whole animal. Lastly, Prof. Burdon Sanderson finds that _section for section_ the organ in the skate is as efficient as it is in _Torpedo_. It is evident that these facts also point to the skate's organ being in course of phylogenetic evolution. [Illustration: Fig. 118.--_Raia radiata_, representing the life size of the youngest individual in which muscle fibres have been found developing into electric cells].