PACKING EGGS— REDDS— ALEVINS. 43 



mosquito-netting, swan's down calico or butter cloth, and that each tray contains 

 two or three layers. These trays, the lowest being empty to receive the drip, are 

 then piled inside a larger outer case with sawdust filling up the interspace 

 between the two cases, which prevents any sudden change of temperature, and 

 subsequently the whole can be placed inside an ice-house or a cold current 

 of damp air may be kept constantly passing through the trays which retards the 

 hatching of the eggs.* When the eggs are going to be unpacked, the bulb of a 

 thermometer should be inserted into the middle of the package, and should it be 

 within 6° Fahr. of the water in the incubating trays they may be transferred at 

 once : if not, this may be gradually altered by adding water. Eggs are not 

 injured by exposure to air, provided it is not for too long a period, and that they 

 do not become warm, dry, freeze, or be subjected to great vicissitudes of 

 temperature. 



Artificial redds may be constructed in suitable spots near to the ground most 

 adapted for young fry, and where the water is shallow and with a slight ripple 

 and of a proper temperature. Here eyed-ova may be deposited, being careful that 

 the localities shall be where floods and discoloured water do not injure the eggs 

 or the alevins when hatched. 



Reverting to the period when the young are hatched as "alevins" to 

 commence their new mode of existence in a world of waters, we see a large bag, 

 the yelk- or nmbilical-sac, dependant from their under sui'face a little behind the 

 gill-opening, and which contains the nourishment whereon they have almost wholly 

 to subsist for a period varying from three weeks to three months in accordance 

 with the temperature of the water and some other disturbing causes. During this or 

 the alevin time, they are not difficult to keep alive, provided they have a fair amount 

 of care combined with a sufficiency of pure water : of this last some are in favour 

 of its being shallow with a strong ripple, while others prefer it to be deeper by one 

 or two inches than what was employed for the incubation of the eggs, and with a 

 slow current ; while in rivers and streams they remain in shallows at this period, 

 localities where they are moderately safe from their larger enemies. When in 

 hatching or rearing-trays they seek dark places in which to hide, they get into 

 every crevice and push into any hole which they can find, consequently numerous 

 precautions have to be adopted to prevent them obtaining access to where their 

 existence would be cut short. Likewise the fish-culturist has to be careful that 

 every screen is in working order, and that the fish are not too crowded. 



During the first few days of their existence alevins incessantly employ their 

 pectoral fins, in order to pi-omote a current, which not only assists respiration, 

 but carries away from their vicinity any deleterious substances which may be 

 floating about. Even subsequent to this period, should the water from any cause 

 be insufficiently aerated they again use these fins for the purpose t of assisting 



bed of moss, about half-an-inoh deep, on tbe bottom of the box, and sink the box in the pan of 

 water. The bottom layer should be a single bunch of some kind of the finer common mosses, 

 ■while the subsequent layers should be the damp rank moss which grows in the swamps, and is 

 known by the name of sphagnum." They may also be packed in baskets. Packing is usually 

 done under water, by which means eggs are more readily spread ; but they can be exposed in air, 

 so long as it is damp and moist and the room dark, for some hours without doing them any 

 injury, 



* The hatching of salmon eggs was retarded, in the vaults of the Wenham Lake Ice Company, 

 in 1865, until the 144th day, and at the Crystal Palace until the 148th day. The Times observed 

 (January, 1884), that the eggs sent to New Zealand by Sir James Maitland were packed on an 

 entirely new principle in order to keep down the temperature. It is a modification of Haslam's 

 refrigerating machinery, and by an ingenious contrivance, the air is kept at a steady temperature 

 of 30° to 34°, low enough to retard the development of the eggs without freezing them, while it is 

 also so saturated with moisture, that a piece of dry flannel being hung up in the chamber m 

 which the eggs are deposited, becomes quite damp in the course of a few hours. The air, reduced 

 to this condition, is driven into the chamber and expelled again on the other side at regular stated 

 intervals of time, so that all possibility of " mouldiness " and of too great saturation is prevented 

 on the one hand, and of too dry cold or too great heat on the other. They arrived at their 

 destination in excellent condition. ,■■•.■, ■, ■ 



t At Cheltenham on March 14th, 1885, the alevin of trout now twenty days old, had ceased using 

 their pectoral fins for aiding breathing, but as soon as the water supply was reduced they again 



