Page:Popular Science Monthly Volume 47.djvu/772

754 the eggs flow at a light touch, it is better to return her to the pond, for eggs that have to be forced are not ripe, and if they can be fertilized make weak fish. For the manner of handling the fish, see illustrations from photographs. The so-called "dry method" is the best. A pan is wet and the water drained from it. The eggs of a female are taken by repeated strokes of the forefinger, if the trout is small, or by the hand if large. The eggs will be found to lie the full length of the body cavity, and the strokes begin near the vent and are then worked farther up toward the head. A bending of the back, as shown, often starts the eggs. This operation takes less time than it does to write it, and some water drips from the fish. A male is then stripped over the eggs and water enough to cover them is added, after which they are left to stand until they "free." The eggs are soft as they leave the fish, and for twenty minutes or more they absorb the milt and water, and while doing this they adhere to the pan, but become free when filled. They should not be disturbed until free, when they are washed by changing the water and then are placed on trays in the troughs. If an egg is not impregnated before it fills with water it never can be fertilized, and the advantage of this "dry method" over taking the eggs in a pan of water is that each egg is brought into contact with the milt, which suddenly becomes active when it comes in contact with water.

This work and all troughs should be in a building and protected from storms and sunshine, but hatching troughs have been successfully worked in the open air. Rats are fond of trout eggs, sediment will smother the embryo within the shell, and direct sunlight will kill it. In a hatching house a distributing trough should run the length of one side. If this is ten inches wide and nine inches deep, with occasional cleats on top to prevent spreading, it will be about right. The water may flow in at one end and out at the other, over a dam six or seven inches high. With hatching troughs at right angles to this and supplied by inch-and-a-half cocks or gates the flow will be regular at all times. These cocks should be halfway between the bottom of the distributing trough and the surface of the water, and may have a fine screen above them, or may pour into one below, as seems best, always looking out that the flow is not stopped nor any fine material