128 BOARD OF AGRICULTURE. [Jan., 



that pine wood by soaking in water soon grows a kind of slimy 

 substance called fungus. To the trout-breeder this is a pest very 

 difficult to overcome. It is fatal to both fish and eggs, and so the 

 troughs are charred, or varnished, or coated with tar to close the 

 pores. Still after doing all you will the fungus will grow to some 

 extent for the first season or two that the trough is used. After 

 that it seems to have spent itself and there is less trouble. Each 

 trough is divided into nests of about four feet in length by strips 

 of glass over which the water ripples, all the strips being of the 

 same width and the trough pitch about an inch to fifteen feet. 

 What water will pass a hole one-fourth of an inch in diameter 

 with an inch head will supply two troughs fifteen or twenty feet 

 long, having a fall from the first to the second. On the bottom 

 of the trough is placed fine, clean gravel of even size, and if con- 

 venient of a dark color, and about one-half an inch deep. The 

 eggs are placed on the gravel by pouring gently from the pan and 

 distributed evenly over the surface with a feather. From five 

 hundred to five thousand of the eggs can be placed on a square 

 foot of the nest. 



The principal enemies of the eggs are fungus, sunlight, rats and 

 mice, and sediment. By keeping out of the trough the light and 

 taking the precautions already named, the fungus can be lessened. 

 By shading the windows and using tight board covers over the 

 troughs the sunlight is guarded against. Rats and mice are very 

 destructive to the eggs and fry, eating thousands of them before 

 the owner can by any chance discover the extent of the mischief. 

 So the eggs must be securely covered, the outlets and inlets all 

 screened, and plenty of poison used. Sediment is the last and 

 least of the enemies named, but it is sometimes a great nuisance, 

 covering the gravel and eggs, leaving the deadly fungus to grow 

 unseen, and in time making the water filthy and weakening the 

 embryo in the egg. All brook-water is full of it, and most spring- 

 water will deposit a half-bushel of it in the course of six months. 

 So the spring is sometimes covered, and the flannel screens thor- 

 oughly looked after. 



When the eggs are first brought in contact with the milt, if they 

 are ripe, and if the water does not first fill the little cells within 

 the shell of the egg, the growth of the young trout begins. In a 

 few hours a round disk is seen on top of the egg. If the egg is 

 impregnated this soon begins to have a cloudy appearance, then 



