218 . THE THORNBACK SKATE 



researches, that the growth of this organ is produced, not by the increase of each column 

 but by a continual addition to their number. A vast amount of blood-vessels pass through 

 the electric organ, and it is permeated with nerves in every direction. 



How the electrical effect is produced is a very deep mystery. In fact, we know 

 scarcely aught of this marvellous power, save the knowledge that it pervades all 

 nature, and even in its external manifestations is one of the most ethereal and most 

 potent of the second means through which the will of the Creator guides His universe. 

 That the same electrical principle exists in all animals is familiarly known, and also 

 that it is far more intense in some individuals than in others of the same species. 

 It is known that the contact of two different kinds of flesh, such as the muscle of a 

 fish and an ox, both newly killed, will produce similar effects ; and that it exists so 

 largely in human beings, that no two individuals can place themselves on isolated stools, 

 and join their hands, without emitting so much electricity by that slight contact, that 

 the instrument will record its presence. But the origin of this wonderful power eludes 

 our mental grasp like the receding waters of the mirage, and the increase of our 

 knowledge serves but to betray the extent of our ignorance. 



I cannot but think that this subtle and potent emanation, which is able to strike the 

 victim through an intervening space of the fluid common to both aggressor and sufferer. 

 has some affinity with the still more subtle and equally mysterious influence by which 

 certain of the serpent race are enabled to paralyze or attract the creatures which they could 

 not secure by actual contact. It may possibly be that the electric powers of the Torpedo, 

 which need water or some other conducting substance for their exercise, are, after all, 

 but a more concentrated and palpable manifestation of that force, which enables the rattle- 

 snake to arrest an animal not in physical contact with itself, the pointed finger to lay a 

 bird motionless on its back until released by a sudden sound or touch, and one human being 

 to influence his fellow without the use of words, and to attract or repel him by an 

 irresistible though invisible agency. 



It is rather remarkable that even the Torpedo, gifted with such puissant arms, dealing 

 pain and death around at will, should find at all events one foe insensible to the electric 

 stroke, and perhaps even needing its exciting influence to preserve it in health. This is a 

 parasitic creature, termed scientifically the Branchellion, which clings to the Torpedo and 

 feeds upon its juices, quite indifferent to all the shocks which its victim dispenses. It 

 generally measures from an inch to an inch and a half in length. 



This fish is found in the Mediterranean, and the Indian and Pacific Oceans, and 

 occasionally off the Cape, and has now and then been captured on our coasts. Happily, 

 the Torpedo does not attain a veiy great size, one of the largest specimens being about 

 four feet long, and weighing sixty or seventy pounds. 



THE Eays are well represented in England by several large and curious species. One 

 of the commonest examples is the THOKNBACK SKATE or RAY, so called from the large 

 number of thorny projections which are scattered over its back and especially along the 

 spine. This species is represented by the upper figure in the illustration. 



The Thornback is one of our common Rays, and is taken plentifully on the shores of 

 England, Scotland, and Ireland. As is the case with many of the same genus, the flesh is 

 considered rather good, and is eaten both when fresh and when salted for consumption 

 during stormy weather. Autumn and winter are the best seasons for procuring this fish, 

 as the flesh is then firm and white, while during the rest of the year it is rather liable to 

 become flabby. Thornbacks taken in November are thought to be the best. 



This species, like the rest of the Rays, feeds on Crustacea, flat-fish, and molluscs, and 

 as many of these creatures possess very hard shells, the Rays are furnished with a crushing 

 mill of teeth, which roll on each other in such a way that even the stony shell of a crab is 

 broken up under the pressure. It is notable that the teeth differ in the two sexes when 

 adult. Those of the female are flat on the top, but those of the male throw out a strong 

 angular projection, which is so arranged that the projections of one jaw exactly fit into 

 the interstices of the other, and the roller-like arrays of teeth bear a wonderful resemblance 

 to the well-known clod-crushing machine. 



