CARRIAGE AND VIVIPICATION OF EGOS. lxvii 



in volume" ii (page 77). Davy ascertained many years since that ova in moist 

 air retain vitality several days, and they may safely be sent in damp moss. 

 In 1880 Mas von dem Borne experimented on whether salmon eggs which 

 had been fertilized by the dry process (or such as had not been brought in- 

 contact with water) could be transmitted long distances without the addition 

 of any fluid. This year 34,000 trout ova 'were despatched to New Zealand 

 in a modified refrigerating chamber. Moistened air passing in a current 

 through the chamber was kept down to a temperature never below 32 deg. 

 or- above 34 deg. fahr. The eggs were arranged in trays lightly covered 

 with moss, and the dead ones were daily removed. Nearly the whole number 

 reached their destination in perfect safety. 



It has been suggested that such fish ova as are deposited at the bottom 

 of ponds might be transported long distances with safety. enclosed in mud, 

 a subject worthy of trial, but great care would have to be exercised as to 

 the character of the water in which the experiment is tried. Fish which 

 deposit their ova on bushes are placed in boxes thus lined, but with movable 

 sides, so that they with the bushes and adherent ova can be transported in 

 carrying boxes to the desired localities. 



The milt of fish has been successfully employed some time after being 

 taken from the parent; thus Sir J. Gibson -Maitland on November 25, 1879, 

 successfully fertilized some trout spawn with, salmon milt obtained the night 

 before and corked. up in a bottle. Likewise, as was long since pointed out by 

 Block, ova or milt may be used obtained from fish which have been some 

 time dead. On November 29, 1883, 1000 eggs of the common brook trout 

 were thus treated at Howietoun with the milt of a par which had not been 

 dead many hours, but the result has been that there was insufficient vitality 

 in the milt to fructify a single egg. It has been remarked at Howietoun 

 that eggs from young mothers give a larger percentage of deaths than those 

 of older fish, this it appears probable affects the fertilizing property of 

 the milt. 



The period which fish eggs take incubating is not only exceedingly Varied 

 among those of closely allied species, but it is likewise affected by many 

 extraneous causes. Those of 'sea fishes, as a rule, would appear to hatch 

 in a shorter period than those of fresh water ones. The eggs of the herring 

 normally incubate in about three or four weeks, but the escape of the young 

 can be considerably delayed by keeping the water very cold, while its 

 Baltness or the reverse exercises no appreciable difference. In the Baltic the 

 German Fish Commissioners found that with the water at 53 degrees the 

 eggs* hatched in a week, whereas with the temperature of the water at 

 38 degrees they took six weeks. In the eggs of the cod fish the American 

 Fish Commissioners observed that hatching took place between the 

 thirteenth and fiftieth days, according to the temperature of the water, while 



e * 



