[9] OPERATIONS AT THE NORTHVILLE HATCHERY. 1045 



remainder only by agitating tlie collections and chunks violently in water, 

 passing the freed eggs through a sieve. The results serve only to 

 verify prior experiments, which show that the greatest enemy of the 

 egg — conferva — generates much faster in water than in atmosphere of 

 the same or even a higher temperature, and that in consequence eggs 

 are far safer out of water than in unless provision for the removal of the 

 coufervaceous egg is made. For incubating the eggs, the Chase auto- 

 matic jar was used, 136 being required at first. They were arranged as 

 follows : 



84 jars, at 175,000 each 14, 700, 000 



52 jars, at 150,000 each 7. 800, 000 



22, 500, 000 



The number of eggs the jar will contain while in operation is in an 

 inverse ratio to the volume of water used. When the minimum of 

 water is used, or just barely enough to impart sufficient motion to the 

 eggs to keep them detached, the jars will hold 175,000 eggs each. Well- 

 filled jars, with a gentle circulation, work much better than those i^ar- 

 tially filled and given a brisk or violent action ; in fact, the former show 

 the very best movement obtainable. But jars to be operated in this 

 way must be perfect in form and have evenly ground tubes, otherwise 

 no motion whatever will be imparted to a portion of the eggs. Then, 

 too, if there is a considerable sprinkling of dead eggs — frequently the 

 case at the beginning of the season — a gentle movement will not always 

 prevent the putrid eggs from uniting or collecting in chunks or masses, 

 which will settle to the bottom of the jar instead of being thrown ofl". 

 For this reason "Hospital" jars have to be given a liberal supply of 

 water in the shape of very energetic currents. 



Several experiments were made with a view to improving on the 

 hatchers in use. The "Improved Shad Hatcher," described in Forest 

 and Stream of June IG, 1881, was tried and found to give a more perfect 

 movement to the eggs than the Chase jar. To secure this, however, 

 eijther a greater volume or head of water was required, owing to the 

 force of the current as it entered the jar being partially arrested in the 

 hollow of the upright cup or cone. 



To overcome this drawback. Assistant Bower advised the use of a 

 solid double cone, the inverted section of which would simply divert or 

 radiate the water without breaking its force, and by its own weight 

 retain its position. The suggestion being acted upon, an equalized 

 current comi)elliug a uniform and perfect movement of the eggs was 

 produced, with the minimum supply of water. 



Into this jar or hatcher the water is introduced at the bottom ; in the 

 Chase jar at the top, being directed to the bottom by a glass tube rest- 

 ing on feet, which frequently obstruct and disconcert the currents 

 throughout the egg-chandier. Assistant Wires succeeded in amending 

 this defect, thereby greatly imj^roving the efficiency of the Chase in- 



