Page:Popular Science Monthly Volume 47.djvu/775

Rh among the amber ones, and an egg that has not been fertilized often remains clear until the rest are nearly hatched, but it can not stand any rough usage, and shows up in numbers after each washing, and, if left for two or three days, will develop a fungous growth that will attach the surrounding eggs in a mass and kill them all. In our early work, when we hatched on fine gravel, fungus was the bugbear: a dead egg would get down in the gravel and send out its deadly tentacles unseen; but with wire cloth and daily supervision fungus is unknown. It is this that kills the eggs in the brooks, and avoiding this cause of mortality from



unimpregnated eggs is one of the reasons why we beat the methods of Nature in increasing a species by protection from its enemies.

At about fifteen days old the expert can take trout eggs in a glass tube or vial and, by holding them above his eye, can see the line of vertebrae which marks the impregnated egg; a few days later he can pick out the "ringers," or eggs which, having no fish in them, retain the ring which they first had on top of the egg. At thirty days, more or less, according to temperature, the eyes show, and the development goes on until the hatching begins at sixty to ninety or more days, according to the thermometer, but the colder waters produce the strongest trout.