HATCHING FISHES' EGGS IN JARS 185 



to the girders of the building. To these ar© 

 fastened cross-pieces on which the troughs rest. 

 One-and-one-eighth-inch dressed lumber is 

 proper for the troughs and the ends may be 

 set flush and not mortised. To facilitate clean- 

 ing, a two-inch hole is bored in the bottom of 

 each trough at the projecting end. Before 

 being used the entire battery inside and out 

 should be given a good coat of asphaltum. 

 When made of lumber, only the finest quality 

 of white pine, cypress, or some similar type 

 of wood entirely free from knots, can be used 

 safely; but a battery may be made of galvan- 

 ised iron, if it is well asphalted before being 

 used, or of concrete. 



Ordinarily when eggs handled in jars begin 

 to hatch, the proceedings are marked with great 

 expedition and the attendants are kept busy. 

 Hundreds of thousands of fry issue simulta- 

 neously ; hence it is important to have plenty of 

 tank-room to receive them. I have found the 

 most convenient fry-tank to be 16 feet long, 

 three feet wide, and four feet deep. With a 

 battery built as outlined, the eggs of only one 

 species of fish can be cared for at a time ; but, 



