March 1, 1888.] 



♦ KNOW^LEDGE <► 



109 



matter, or bioplasm, each cell is built. But even mortar 

 may need quickening — so this life-stuff may become too 

 passive, that is, quasi torpid. These nervous fibrilhv are 

 the electric wires, and gentle friction is the dynamo to 

 generate the mysterious fluid and quicken the conductivity 

 along the lines. 



Strange to say, this scratching has also its p.sychological 

 side. Let a puzzle be pro]5ounded, and why on the instant 

 does the nonplussed one institute a rummaging for an idea 

 in the hirsute thatch of his cranium 1 And everybody 

 does it, even he "of the front of Jove himself" more than 

 the beetle headed clown. We asked an explanation of our 

 encyclopedic friend who " knows it all," and quoted to him 

 the well-worn distich : — 



Be mindful, when invention fails. 



To scratch jour head and bite your nails. 



Upon the word he began dishevelling his carefully brushed 

 hair, saying it was " a poser," and, by way of compli- 

 ment, that it " was not slow " ; to which our response, 

 " No, it's Swift " ; at which he laughed, though he had 

 quite missed the point, for he rejoined that he always 

 thought us " a little fast." 



It is truly wonderful how lavishly and admirably Nature 

 has gifted many animals for this very exercise of scratch- 

 ing lighth' with the claws. At my feet lie Tom and 

 Dick, two good friends. The former is a fine young Mal- 

 tese, the latter an old black-and-tan. The cat's claws are 

 very sharp, the dog's are less so. Both animals are clean 

 and in good condition, yet both appear to take delight in 

 a good scratching at the back of tlie head, and especially 

 behind the ears. The hind-foot is the instrument used, 

 and with what delicacy — yes, nicety, or precision of ad- 

 justment I So rapidlj' does that foot move, that it makes 

 a fan-like shadow ; and so exact the distance at which 

 the keen, protruded claws are set, that it secures only a 

 delicate touching of the parts, producing the pleasant titil- 

 lation of the tousorial brush. Any coarser adjustment of 

 those needle-pointed hooks and the blood would flow from 

 the lacerated skin. 



But, even more than with the mammals, is this cuticular 

 titillation a necessity with the ordinary fishes; and, since 

 they have neither hands nor feet, how is this want in their 

 case gratified ? I have witnessed the operation many times, 

 yet fear a failure to adequately describe it. The scaly coat- 

 ing of a fish needs an occasional cleaning, as does the 

 copper sheathing of a ship; for, with both, a foul surface 

 impedes progress through the water. On each side of a 

 typical fish is a thin line, known as the lateral line. It Ls, 

 in fact, a mucous canal, from which issues at the will of the 

 animal a lubricating fluid, which, spread over its scaly 

 sheathing, lessens friction, and so facilitates movement in 

 the water. This mucous line is made up of rows of pores, 

 which communicate with the slime-secreting glands. Leydig 

 discovered that each of these oil-producers had its own 

 nerve, thus constituting a series of sense-organs. And very 

 delicate is their sense, as by them the fish gauges the weight 

 of the water-mass, also the direction and resistance of 

 currents. But associated with these nerves, arranged in 

 tufts or buttons, are air-cells ; hence it seems certain that 

 the fish is able to appreciate vibi-ation in water, whose wave- 

 lengths are larger than are those of sound. The faculty of 

 appreciating the waves of light we call seeing, and similarly 

 of sound, hearing, whose waves are much larger than those 

 of light. But our scaly subject is endowed with a third 

 wave-measuring sense, in which possession it out-paragons 

 " the paragon " himself. It can appreciate the trills or waves 

 of water vibration, and of this facultj' our language has no 

 word to express the name. 



Now these oil-yielding tubas above described may get 



clogged, or the glands become torpid. Here, then, are sense- 

 organs to declare the state of afiixirs. Hence arises the 

 necessity for the animal either to clean oflT its body armour 

 or to stimulate into activity the indolent organs. And, in 

 fact, in other ways, fishes have their own eczema, or diseases 

 of the skin. Sometimes there is a blistering or deterioration 

 of the cutis, and sometimes a species of Saproleynui, a 

 fungous parasite, sets up a flocculent growth on the cuticle. 

 For any of these instances friction is the only remedy, and 

 its exercise is unquestionably pleasant to the fish. 



But how can a fish scratch itself ] Sometimes in the way 

 C'ushie, as when she rushed through the evergreens. So 



of 



a fish will often dart through a dense clump of soft water- 

 weeds. But this amounts to little else than a gentle titilla- 

 tion. The scaly sheath is not to be cleansed so easily. I 

 have seen the performance many times, and by several 

 species, but none have so much interested me in this respect 

 as the sunfish. Take the one best known to the pin-hook 

 anglers, and often called "pumpkin-seed." There is a 

 boulder with a smooth, clean surfiice. The fish is steady ; 

 its big eyes seem of a sudden to glow with a blue light. 

 Every fin is set, even to the dorsal, which bristles with its 

 keen spines. The fish seems aiming for that stone. The 

 propulsion must come from the caudal and the side fins, but 

 mostly from the former. All these give a simultaneous 

 blow against the water ; at the same time, as if it were in 

 the way, the topsail — that is, the dorsal — falls and is snugly 

 reefed. All this is done in a moment, and such the force 

 that the fish truly darts, threatening to butt its nose against 

 the rock. The speed is high, but, just ere the rock is 

 reached, there is a marvellously sudden bend of the body, 

 the most convex point being the exact spot which is to be 

 scratched. Though very rapid, so well-timed is the move- 

 ment, and so nice the adjustment of the position, that the 

 pressure or amount of rub or friction is correctly received, 

 and the point of impact is precise, and the body glances 

 from the rock. The collision is so accurately gauged that 

 no harm is done. And similarl}', and with a great variety 

 of ingenious posturing, the fish subjects all parts of its body 

 to this treatment. It even contrives to scratch the top of its 

 head, by bringing the desired spot into the proper position 

 at the precise moment of tlie glancing impact with the stone. 

 The feat is delicate and deftly, as if an acrobat should in his 

 somersaults comb his hair against a rock with no harm done 

 every time. 



Having enjoyed the use of a large aquarium for the study 

 of fishes, it has been an object with me to anticipate their 

 wants. Hence I have purposely given them scratching- 

 stones properly adapted to their needs. I was surprised 

 that a favourite object for this purpose was a large live 

 river-mussel, the Anodonta excurvata. The corrugations of 

 the shell, which mark its growth, form a series of smooth 

 ridges, upon and against which, with theii- contortions of 

 twists and bends and tilts, these fishes glance in scratching 

 themselves. As to ichthyic emotion one cannot saj' much. 

 That they enjoy these exercises I am sure ; and I almost 

 think they know their benefactor, for they come at his call 

 at feeding-time — though up to this present writing I have 

 not observed anything that miglit be interpreted as a grate- 

 ful recognition of benefits conferred ; certainly nothing com- 

 mensurate with the canny benediction, " God bless tlie Duke 

 of Argyll ! " — Popular Science Monthly. 



Ax Indiana Monstrosity. — A two-headed child, near Prince- 

 ton, Ind., was born on January 9 to the wife of Henry Wilson, a 

 farmer living four miles from that city. It had two well-formed 

 heads, one just behind the other, and weighed twelve pounds. The 

 strangest feature about it was that the heads were covered with hair 

 three inches in length. The front head was more perfectly formed 

 as to features than the one behind, which had onlj- an indistinct 

 nose and mouth. The child only lived a few minutes after birth. 



