170 NATURE STUDY REVIEW [10:5— May, 1914 



eggs are covered with gravel. As soon as the nest is completed 

 and the male has lost his mating ardor, the former is deserted. 



The writer has had much pleasure in collecting the eggs from 

 chub's nests and hatching them at home. In order to secure 

 them it has been found convenient to use a small dipnet with a 

 shallow bag of fine bobbinet or cheese cloth. The mesh must be 

 very fine for the eggs are small, the largest of them smaller than 

 an ordinary pin. The net is placed in the basin of the nest with 

 the opening up stream. With one hand some of the gravel is 

 scooped from the ridge above and agitated gently under water 

 directly in front of the net. The gravel and sand being heavier 

 will immediately fall to the bottom, while the lighter eggs will 

 be carried into the net by the current. The net is then turned 

 inside out into a basin or tray of water. An agate-lined photo- 

 graphic developing tray answers the purpose admirably. From 

 the tray the eggs may be gently poured into a wide mouth bottle, 

 fruit jar or a clean tin pail and carried home. 



Two different but equally successful ways of hatching the eggs 

 without the use of running water have been used. The first 

 and simplest is to place them in a shallow tray covering with 

 water to no greater depth than one-half inch. A little more 

 water may be added each day to replace that which has evaporated. 

 One 5x7 tray will accommodate one hundred eggs without 

 changing the water at all. The eggs in order to develop must 

 have oxygen but in a shallow dish enough of the gas is taken up 

 at the surface of the water directly from the air to fulfill this 

 requirement. 



The second method necessitates the use of a tray made of 

 strips of cork pinned together at the corners, the bottom to be 

 covered with bobbinet of small mesh. A tray 3 x 4 x ^ inches 

 will be sufficient for one hundred eggs. One must be sure that 

 the tray will float, then it must be placed in an ordinary balanced 

 aquarium and the eggs distributed over the bobbinet. In this 

 manner the eggs are kept in the surface layer of water which is 

 always well oxygenated. In from six to ten days when all the 

 young fish have appeared the tray is simply turned over under 

 water and the young allowed to disperse in the aquarium. It is 

 of course necessary that the aquarium have no predacious inhabi- 

 tants such as aquatic insects, hydras or fish of any kind. What- 

 ever means is provided for hatching the eggs one must never 

 allow direct sunlight to fall upon the eggs. 



