708 BULLETIN OF THE BUREAU OF FISHERIES. 



grounds, and all fish are transferred to the crates before being spawned. Spawn- 

 taking operations are conducted daily throughout the entire period while the 

 fish are penned. About 75 per cent of all the females confined in crates yield 

 good eggs; the remainder either cast their eggs in the crates, become plugged, 

 or fail to ripen. 



At the Put-in Bay station the Downing jar, an open-top glass vessel with 

 pitcher lip, devised by the superintendent, has supplanted other forms of hatch- 

 ing jars. In each of these jars ^j-i quarts of green eggs to S/i quarts of eyed eggs 

 are subjected to a flow of 4 quarts of water per minute. The jars are arranged 

 in so-called batteries, which are described in the Manual of Fish Culture else- 

 where cited. The batteries at Put-in Bay are of the t}'^pe known as single 

 batteries, each having an independent water supply. They have some new 

 features, notably, for economy in arrangement, the alternation in position of the 

 jars in vertical rows, thus making it possible to bring the troughs more closely 

 together. In the batteries at this station there are 1,692 jars and the flow of 

 water through them is so economically arranged that only 330 gallons per 

 minute is required when all are in operation. This type of battery is the one 

 commonly used at the Bureau's stations, called single battery to distinguish it 

 from the double battery at Detroit." The Detroit hatchery is equipped with 

 1,487 Chase and Downing jars, and a total of 441 gallons of water is required 

 when the entire battery is in operation. 



At Cape Vincent station the battery is a single tier, but the arrangement of 

 the jars is not so compact and the tiers are not so well set up as to economy in 

 water supply, 492 jars requiring a total volume per minute of 1 23 gallons. At 

 Swanton station a single battery of 606 jars requires a total volume of 227 

 gallons per minute. The batteries at Detroit and Put-in Bay are constructed 

 entirely of wood; the battery at Cape Vincent was originally of wood, but as 

 the troughs began to decay galvanized iron was substituted without remov- 

 ing the original stand on which the wooden troughs rested. At Swanton the 

 supply troughs in the battery are also of galvanized iron, the first cost of 

 which is more than for wood, but taking into consideration durability of material, 

 may be considered more economical. 



PIKE PERCH. 



' By methods similar to those pursued in the conservation of whitefish eggs, 

 pike perch eggs also are extensively collected, the most important field, as with 

 the whitefish, being within a 40-mile radius of the Put-in Bay station. Here and 

 at other points on the Great Lakes the eggs are all obtained from ripe fish as 

 caught, the penning of the pike perch b}' methods described for the whitefish 

 having proved not feasible in the sheltered bays where such work might other- 



o Manual of Fish Culture, p. 117. 



