ARTIFICIAL PERCH CULTURE 229 



day I went to look at them, and very soon I found 

 that the sewage-charged water was depositing a filthy 

 slime over the eggs which by degrees choked, turned 

 white and opaque, and then rotted away. 



The experiment was a failure, but it taught me a 

 very valuable lesson. It showed how the perch egg- 

 harvest of a polluted river might be saved. What 

 should have been done was to remove the hurdles 

 from the river as soon as the eggs were deposited, 

 and place them in purer water; then doubtless, 

 they would have hatched. I have heard of similar 

 hurdles, bearing the spawn of coarse fish, being 

 brought for sale to markets on the Continent. 



With regard to moving perch eggs, however, I am 

 faced with this difficulty. I have on several occasions 

 collected the eggs with the intention of hatching 

 them out in some safe place, but the shaking to 

 which they were subjected in the course of being 

 removed [from the water invariably seemed to kill 

 them unless they had reached the eyed stage before 

 being disturbed ; at least I put their loss down to this 

 cause, reasoning from the analogy of salmon and 

 trout eggs, which are hopelessly injured if shaken 

 between a few hours after they are spawned and 

 the appearance of the black specks, the eyes of the 

 embryo within the shell. At this later stage the 



