54 SCIENCE SKETCHES. 



mutilated, their eyes are often injured or destroyed, 

 parasitic worms gather in their gills, they become 

 extremely emaciated, their flesh becomes white 

 from the loss of oil ; and as soon as the spawning 

 act is accomplished, and sometimes before, all of 

 them die. The ascent of the Cascades and the 

 Dalles probably causes the injury or death of a 

 great many salmon. 



When the salmon enter the river they refuse to 

 take bait, and their stomachs are always found 

 empty and contracted. In the rivers they do not 

 feed ; and when they reach the spawning grounds, 

 their stomachs, pyloric cceca and all, are said to be 

 no larger than one's finger. They will sometimes 

 take the fly, or a hook baited with salmon roe, in 

 the clear waters of the upper tributaries, but there 

 is no other evidence known to us that they feed 

 when there. Only the quinnat and blue-back 

 (there called red-fish) have been found at any great 

 distance from the sea, and these (as adult fishes) 

 only in late summer and fall. 



The spawning season is probably about the same 

 for all the species. It varies for each of the differ- 

 ent rivers, and for different parts of the same river. 

 It doubtless extends from July to December. The 

 manner of spawning is probably similar for all 

 the species, but we have no data for any except the 

 quinnat. In this species the fishes pair off; the 

 male, with tail and snout, excavates a broad, shal- 

 low " nest" in the gravelly bed of the stream, in 

 rapid water, at a depth of one to four feet; the 

 female deposits her eggs in it, and after the exclu- 

 sion of the milt, they cover them with stones and 



