HATCHING APPARATUS. 73 



hatching trough. From ten to twenty days are required 

 from the commencement of the hatching season to its close, 

 consequently a proportionate number of fish are hatched 

 daily ; these are washed from the unhatched eggs into the 

 first receiving tank before mentioned, and allowed to stand 

 quietly without much current to the water in which they 

 are. The eggs thus cleansed are returned to the hatching 

 boxes from which they came. As soon as the shells from 

 the eggs are well settled to the bottom, a moderate current 

 of water is allowed to flow through an opening to the next 

 tank below, carrying the cleansed fish with it, depositing 

 any impurities that may yet be left with the fish in said set- 

 tler ; and the fish are allowed to follow on with the current, 

 passing still through another opening to the large reception 

 room, where they remain in perfect condition in pure run- 

 ning water until placed in the waters designed for them. 



" M is a shallow trough supplied with water drawn from 

 the main tank, being the same temperature of that in which 

 the eggs are hatched. 



" During the first few weeks of their incubation, many 

 imperfect and dead eggs are found, and for the purpose of 

 removing them from the good ones, the screens upon which 

 they lie are removed from the hatching boxes to the shallow 

 trough of running water and picked out in the usual way 

 with forceps, as shown by the figures in the illustration." 



5. Holtorfs Method* This is an invention of Mr. 

 Marcellus G. Holton, who was drowned at the time 

 of the unfortunate accident to the party who were col- 

 lecting salmon-trout eggs on Lake Ontario in 1873. 



This contrivance is very highly spoken of by those 



* The Ferguson Jars, invented by T. B. Ferguson of Balti- 

 more, are a modification of this principle, the variation in Fergu- 

 son's apparatus being that cylindrical glass jars, with round trays 

 to match, are substituted for the square wooden boxes of Holton. 



