Now, in the particular case of the skate, the organ is situated in the tail, where it is of a spindle-like form, measuring, in a large fish, about two feet in length by about an inch in diameter at the middle of the spindle. Although its structure is throughout as complex and perfect as that of the electric organ in _Gymnotus_ or _Torpedo_, its smaller size does not admit of its generating a sufficient amount of electricity to yield a discharge that can be felt by the hand. Nevertheless, that it does discharge under suitable stimulation has been proved by Professor Burdon Sanderson by means of a telephone; for he found that every time he stimulated the animal its electrical discharge was rendered audible by the telephone. Here, then, the difficulty arises. For of what conceivable use is such an organ to its possessor? We can scarcely suppose that any aquatic animal is more sensitive to electric shocks than is the human hand; and even if such were the case, a discharge of so feeble a kind taking place in water would be short-circuited in the immediate vicinity of the skate itself. So there can be no doubt that such weak discharges as the skate is able to deliver must be wholly imperceptible alike to prey and to enemies. Yet for the delivery of such discharges there is provided an organ of such high peculiarity and huge complexity, that, regarded as a piece of living mechanism, it deserves to rank as at once the most extremely specialized and the most highly elaborated structure in the whole animal kingdom. Thousands of separately formed elements are ranged in row after row, all electrically insulated one from another, and packed away into the smallest possible space, with the obvious end, or purpose, of conspiring together for the simultaneous delivery of an electric shock. Nevertheless, the shock when delivered is, as we have just seen, too slight to be of any conceivable use to the skate. Therefore it appears impossible to suggest how this astonishing structure--much more astonishing, in my opinion, than the human eye or the human hand--can ever have been begun, or afterwards developed, by means of natural selection. For if it be not even yet of any conceivable use to its possessor, clearly thus far survival of the fittest can have had nothing to do with its formation. On the other hand, seeing that electric organs when of larger size, as in the _Gymnotus_ and _Torpedo_, are of obvious use to their possessors, the facts of the case, so far as the skate is concerned, assuredly do appear to sanction the doctrine of "prophetic germs." The organ in the skate seems to be on its way towards becoming such an organ as we meet with in these other animals; and, therefore, unless we can show that it is now, and in all previous stages of its evolution has throughout been, of use to the skate, the facts do present a serious difficulty to the theory of natural selection, while they readily lend themselves to the interpretation of a disposing or