EFFECTS OF CONCUSSION ON EGGS. , 41 



occur to fisli eggs, although deposited under favourable conditions, when floods 

 or other causes might disturb the redds ; while even the artificial fish-cultui'ist is 

 sometimes compelled to remove ova from one tray to another, to wash them when 

 covered with mud or other sediment, or even to send them to distant places. 

 Sometimes the deposit on the eggs is so great that were it not removed the 

 embryos would be suffocated ; and the consequence of draining the trays and 

 cleansing the ova, by means of a watering pot,* is different in accordance with the 

 period of incubation at which it takes place. The capacity for receiving slight 

 shocks with a considerable amount of impunity, ceases after about the first twenty- 

 four or forty-eight hours subsequent to extrusion from the fish, and docs not 

 return until at least one-third of the period of incubation has been completed, 

 and even then some slight injury may be occasioned. 



Experimentsf were undertaken in order to ascertain the effects of direct 

 concussion on these eggs, which influences would be identical with what they 

 must experience if carried over rapids or steep inclines. They were either placed 

 in a bottle of water and dropped from various heights, or direct into water, when 

 it was found that in those in which this was tried within twenty-two days after 

 having been obtained from the fish, none lived over eight or nine days. But in 

 eggs dropped fi'om even a greater height, after they had incubated forty-seven 

 days, some lived to hatch, demonstrating what a much larger amount of motion 

 and concussion eyed ova will bear than eggs in their earlier stage. 



Among the various experiments of shocks and concussions made during the 

 first days of incubation no single monstrosity was observed : neither were any 

 hatched from the eggs which had been subject to frost and cold, which will again 

 have to be referred to. 



It is now about thirty years since Dr. John Davy experimented upon the 

 fertilized eggs of these fishes,+ with reference to their capabilities for diffusion, 

 and what adverse circamstances they might be subjected to, but retain their 

 vitality. Living and incubating, as I have shown they are able to do without 

 immersion in water (see page 35), they might be conveyed from one piece of water 

 to another adhering to the feathers or feet of birds, or the fur of mammals, even 

 fish which have swallowed impregnated eggs might be the vehicle for their 

 conveyance when carried off by rapacious birds. 



* January 5th, 188(5, trout eggs in tray No. 2, at Cheltenham, containing about 2.500, were 

 transferred to another tray, and by 3 ^.^^. 24 were dead, while the average number of deaths up to 

 this period had been one daily; now the pick rose to 31, 2, 7, 7, 2, and then the mortality 

 reverted to wliat it had previously been. The eggs in trays Nos. 1 and 3, placed under the same 

 conditions, showed no increase in the daily average of deaths, consequently the above experiment 

 may be adduced as an example of the effect of slight shocks in the very early (not earliest) 

 condition of embryonic life. January 18th, the eggs in tray No. 1, likewise containing about 2500, 

 were similarly changed, but the deaths were scarcely increased thereby, as only five were picked 

 out during that and the succeeding 13 days, whereas 26 had been removed during the previous 

 30 days. February 5th, the eggs in the trays where they were treated by a solution of peat, were 

 washed without any deaths resulting. February 21st, the eggs in tray No. 2 were again washed, 

 and soon five opaque ones were seen, but no such mortality took place in the other trays. February 

 23rd, eggs in tray No. 1 were washed : for the preceding ten days only two had died, and during the 

 next six days they occurred as follows, 2, 5, 0, 1, 1, 1. 



t January 2ud, 1886, at 10'45 a.m., a trout egg, on the 22nd day of incubation, was dropped 

 from a height of 2 ft. into the water, and by 12 a.m. it was dead and opaque ; a second was 

 similarly dropped on to a board, it also was dead by 1 p.m. Next, five eggs were dropped from the 

 same height into the water and subsequently returned to a hatching-tray : the first died on 

 January 12th, and the remainder by March 8th. On December 30th, 1885, at 1-25 p.m., ten eggs 

 were taken from tray No. 2 and placed in a quart brandy bottle which, when empty, weiglied a 

 little over l.J lb., but when full of water and corked, 3 lb. 3 oz. Thus filled it was dropped from 

 a height of 2 ft. on to the grass, and by January 1st, 2 were dead, 2 died in February, and the 

 remainder by March 7th. On January 27th, eiglit eggs, on the 47th day of incubation, were 

 placed in a bottle similar to the foregoing, and dropped 4J ft. : one died the same day, one on 

 the 15th, 3 hatched on the 25th or 20th, and the remainder succumbed. 



J Dr. Davy in his experiments upon salmon eggs ascertained that when exposed to dry air at 

 the ordinary temperature they rapidly died ; that their vitality was as well preserved in moist 

 air as in water, while ova placed in ice were not affected unless lowered many degrees below the 

 freezing-point. If the water in which the eggs were, became heated to 80° or 82° Fah., they 

 could stand it with impunity for a moderate period, but 81' or 85° was fatal. 



