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<h2>CHAPTER LIII.</h2> 1052. Why have birds with long legs short tails? Because the tails of birds are used to guide them through the air, by a kind of steerage. When birds with long legs take to flight, they throw their legs behind, and they then serve the same purpose as a tail. <div class="figcenter"> <ANTIMG src="images/i-271.jpg" width-obs="400" height-obs="238" alt="" /> <div class="caption">Fig. 68.—PERCH.</div> </div> 1053. Why have fishes fins? The fins of fishes are to them, what wings and tails are to birds, enabling them to rise in the fluid in which they live by the reaction of the motions of the fins upon its substance. [Pg 266] <hr class="bible-verse" /> "Speak to the earth, and it shall teach thee; and the fishes of the sea shall declare unto thee. Who knoweth not in all these that the hand of the Lord hath wrought this."—Job xii. <hr class="bible-verse" /> 1054. Why are the fins of fishes proportionately so much smaller than the wings of birds? Because there is less difference between the specific gravity of the body of a fish, and the water in which it moves, than between the body of a bird, and the air on which it flies. The fish, therefore does not require such an expanded surface to elevate or guide it. 1055. Why have fishes scales? Because scales, while they afford protection to the bodies of fish, are conveniently adapted to their motions; and as the scales present no surface to obstruct their passage through the water, as hair or feathers would do, they evidently form the best covering for the aquatic animal. 1056. Why do fishes float in streams (when they are not swimming) with their heads towards the stream? Because they breathe by the transmission of water over the surface of their gills, the water entering at the mouth, and passing over the gills behind. When, therefore, they lie motionless with their heads to the stream, they are in that position which naturally assists their breathing process. 1057. Why have fishes air-bladders? Because, as the density of water varies greatly at different depths, the enlargement or contraction of the bladder regulates the relation of the specific gravity of the body of the fish to that of the water in which it moves. 1058. Why have whales a very large development of oily matter about their heads? Because their heads are thereby rendered the lighter part of their bodies, and a very slight exertion on the part of the animal will bring its head to the surface to breathe air, which it constantly requires. 1059. Why have birds that swim upon water web-feet? Because the spreading out of the toes of the bird brings the membrane between the toes into the form of a fin, or water-wing, [Pg 267] by striking which against the water, the bird propels itself along. <hr class="bible-verse" /> "And Jesus saith unto him, The foxes have holes, and the birds of the air have nests; but the son of man hath not where to lay his head."—Matthew xiii. <hr class="bible-verse" /> 1060. Why have birds that swim and dive short legs? Because long legs would greatly impede their motions in the water, by becoming repeatedly entangled in the weeds, and by striking against the bottom. Waders, however, require long legs because they have to move about through the tall vegetation of marshy borders. <div class="figcenter"> <ANTIMG src="images/i-273.jpg" width-obs="400" height-obs="318" alt="" /> <div class="caption">Fig. 69.—STILT-PLOVER AND DUCK.</div> </div> 1061. Why have the feet of the heron, cormorant, &c., deep rough notches upon their under surface? Because, as those birds live by catching fish, they are enabled by the notches in their feet, to hold the slippery creatures upon which they feed. 1062. Why have otters, seals, &c., web-feet? Because, while the feet enable them to walk upon the land, they are equally effective in their action upon the water, and hence they are adapted to the amphibious nature of the animals to which they belong. 1063. Why do the external ears of animals of prey, such as cats, tigers, foxes, wolves, hyenas, &c., bend forward? Because they collect the sounds that occur in the direction of the [Pg 268] pursuit, and enable the animal to track its prey with greater certainty. <hr class="bible-verse" /> "Doth the hawk fly by thy wisdom, and stretch her wings toward the south? "Doth the eagle mount up at thy command, and make her nest on high?" <hr class="bible-verse" /> 1064. Why do the ears of animals of flight, such as hares, rabbits, deer, &c., turn backward? Because they thereby catch the sounds that give them warning of the approach of danger. 1065. Why has the stomach of the camel a number of distinct bags, like so many separate stomachs? Because water is stored up in the separate chambers of the stomach, apart from the solid aliment, so that the animal can feed, without consuming all its drink. It is thereby able to retain water to satisfy its thirst while travelling across hot deserts, where no water could be obtained. 1066. Why do woodpeckers "tap" at old trees? Because by boring through the decayed wood, with the sharp and hard bills with which they are provided, they get at the haunts of the insects upon which they feed. 1067. Why are woodpeckers' tongues about three times longer than their bills? Because, if their bills were long, they would not bore the trees so efficiently; and when the trees are bored, and the insects alarmed, they endeavour to retreat into the hollows of the wood; but the long thin tongue of the woodpecker fixes them on its sharp horny point, and draws them into the mouth of the bird. 1068. Why have the Indian hogs large horns growing from their nostrils and turning back towards their eyes? Because the horns serve as a defence to the eyes while the animal forces its way through the thick underwood in which it lives. 1069. Why have calves and lambs, and the young of horned cattle generally, no horns while they are young? Because the presence of horns would interfere with the suckling [Pg 269] of the young animal. When, however, it is able to feed itself by browsing, then the horns begin to grow. <hr class="bible-verse" /> "She dwelleth and abideth on the rock, upon the crag of the rock, and the strong place. "From thence she seeketh the prey, and her eyes behold afar off. Her young ones also suck up blood: and where the slain are, there is she."—Job xxxix. <hr class="bible-verse" /> 1070. Why have infants no teeth? Because the presence of teeth would interfere with their suckling, while the teeth would be of no service, until the child could take food requiring mastication. 1071. Why cannot flesh-eating animals live upon vegetables? Because the gastric juice of a flesh-eating animal, being adapted to the duty which it has to perform, will not dissolve vegetable matter. 1072. Why have birds gizzards? Because, having no teeth, the tough and fibrous gizzards are employed to grind the food preparatory to digestion. 1073. Why are small particles of sand, stone, &c., found in the gizzards of birds? Because, by the presence of those rough particles, which become embedded in the substance of the gizzard, the food of the bird is more effectively ground. When our fowls are abundantly supplied with meat, they soon fill their craw, but it does not immediately pass thence into the gizzard; it always enters in small quantities, in proportion to the progress of trituration, in like manner, as in a mill, a receiver is fixed above the two large stones which serve for grinding the corn, which receiver, although the corn be put into it by bushels, allows the grain to dribble only in small quantities into the central hole in the upper mill-stone.—Paley. <hr class="chap" /> <div style="break-after:column;"></div>

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