  One day in November the postman brought Uncle George a small wooden box. There were holes bored in the sides and top of it. The box, when opened, seemed to be filled with damp moss; but when some of this moss was removed there was found in the middle of the box a piece of folded muslin.
Uncle George laid the muslin on the table, and opened it out. It contained a number of tiny pink balls, much smaller than peas. “These are the trout eggs you promised to get for us, are they not?” said Frank. “They are,” said Uncle George, “and we must put Uncle George filled a wide-mouthed bottle with water from the tap and placed the eggs in it. He then corked it with a cork in which he had bored two holes. Into each of the holes he had fitted a tube. One tube was long enough to reach almost to the bottom of the bottle. The other was bent over the outside of the bottle. The straight tube was connected with the water tap by a piece of indiarubber tubing. He then turned the tap on gently, so that the water went in by the straight tube and came dripping out by the bent tube. “Trout require a constant supply of fresh water,” he said. “Their eggs are usually laid in shallow streams. “Now, boys, I want you to watch these eggs and note down any changes you see in them. You can remove the bottle from the tap at any time, but you must not keep it more than fifteen minutes at a time, or your trout will not hatch.” At the end of a week the boys noticed two black dots and a coiled white line in each egg. In two weeks more some curious-looking creatures were seen wriggling about among the eggs. As there were some empty egg-skins to be seen, they guessed that these lively creatures must be young trout. They were not a bit like fish. Each seemed to be made up of a long white streak, which looked like the “backbone” of a fish, a big, clumsy yellow bag with red veins running through it, and two large black spots that looked like eyes. In a few days all the eggs hatched out, and in place of the little pink eggs there was a crowd of these wriggling creatures and a number of empty egg-skins. The boys were puzzled, and Uncle George had to be consulted. Six Stages in Development of Trout. “I don’t think these were trout eggs,” said Frank. “The creatures that came out of them are not a bit like fishes. They swim on their sides and have a huge yellow bag attached to their bodies.” “They are young trout, I can assure you, Frank,” said his uncle laughing. “If you remember, your tadpoles were not a bit like frogs when they hatched out of the egg. These huge bags you talk of are called ‘yolks.’ Each trout when hatched is furnished with a huge yolk or food supply. “The tadpole, when hatched, has also got a yolk upon which he lives without eating for four or five days. Our trout will require no food for six weeks. During that time the yolk will become smaller and smaller, and at last disappear entirely. While the yolk is shrinking, you will notice that the creature gradually assumes the form of a fish.” Uncle George emptied the bottle containing the young trout into a wooden box which he had made. This box was fifteen inches long, four inches broad, and four inches deep. The inside of it he had charred with a red-hot iron after it was put together. It was placed under the tap, and the water dripped into it all day and all night. Frank made a small gauze net about the size of a dessert-spoon, and with this they lifted troutlets out of the box whenever they wanted to examine them. As their uncle had said, the creatures changed from day to day. By placing a single trout in a white saucer, the boys could note these changes; but they were such lively little creatures that making good sketches of them was somewhat difficult. First the big black dots became more like eyes. Then delicate fins and tail appeared, and mouths which opened and shut. At the top of the yolk-sac, just under the head, the boys could see a little red thing like a heart beating constantly. As the yolk-sac grew smaller, the little fish’s body grew more shapely, and tiny brown spots appeared all over it. At last, at the end of six weeks, the yolk was completely gone, and the young trout were now beautiful little fish, shaped and coloured exactly like big trout. Then Uncle George began to feed them. They were fed four times a day on the yolk of an egg which had been boiled for half an hour. A very small quantity of this hard yolk was squeezed through a piece of gauze into the water, and the little fishes dashed at it and gobbled it up greedily. They were so rapid in their movements, swimming about and leaping out of the water, that the boys were never tired of watching them. “What are the brown spots on a trout for?” Frank asked his uncle one day. “The trout is protected by his colour,” said Uncle George. “Each trout is coloured like the bed of the stream he lives in, and the spots resemble grains of sand and tiny pebbles. The trout can change his colour, like the frog, as I will show you.” Uncle George took two trout out of the box and placed them in a glass dish. He placed the dish in a white saucer, and so arranged it that water was kept flowing into and out of it. Next day he took two more trout out of the box and placed them in the glass dish. It was then seen that the first two trout had grown quite light in colour. They were much paler than those taken out of the box, the inside of which was charred and black. One day Uncle George found two of the trout dead in the box. “I am afraid, boys,” he said, “that we cannot keep them confined any longer. Get a large pail full of water, and we will carry them to the brook.” “We must come here and fish next year, Frank,” said Tom, after the trout were transferred to the brook. “They are now about an inch long,” said Uncle George. “In a year they will be four inches long. In about three years, if they are not devoured by larger trout, they will weigh about a pound apiece.” “I think it is a shame to kill such pretty little creatures,” said Frank. “I quite agree with you, Frank,” said his uncle. Exercises on Lesson XIII.
|
|
