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, a// 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 
