190 DESTROYERS OF SALMON OVA. 



the formation of another nest, or link of the bed 

 above that already excavated, and in which un- 

 covered ova are deposited, that trout dart towards 

 the bed and devour the spawn. The falling down 

 stream for a short time and short distance on the 

 part of salmon is of twofold necessity; first, to 

 gain renewed strength by temporary cessation 

 from labour; and secondly, to get space enough 

 to " take a run," if I may use a jumper's phrase, 

 in order to be able to dart their heads with greater 

 force and efiect into the sand and gravel for the 

 formation of a new nest, or link in the bed-trench. 

 The water-ousel is also a sad destroyer of salmon 

 ova. It watches their emission by the spawning 

 salmon, then dives into the water, and descending 

 to the bottom, runs along it to the spawning-bed, 

 out of which it extracts a large quantity of spawn, 

 and would steal more did not the procreating fish 

 see it and drive it away. The spawn once fairly 

 covered in, neither trout, nor water-ousel, nor any 

 other fish or bird can injure it. The supposition 

 that eels burrow into salmon-beds and feed upon 

 the spawn beneath, is erroneous. 



It is alleged that alluvial deposits frequently 

 settle upon, and cover the beds, thereby destroy- 

 ing the ova — addling them, in fine, by preventing 

 the chemical action necessary for their incubation 



