NATIONAL FISHERY CONGRESS. 
211 
This goes on until the obstacle is surmounted, if it is not too great. Then, without 
delay, the lamprey pushes on upstream, sometimes 8 or 10 kilometers, until clear water 
and numerous ripples are found. Just above some ripple the lamprey begins to make 
ready a secure place for a new generation. 
The male arrives first 
and begins the nest build- 
ing by removing and plac- 
ing stones with his suctorial 
mouth. In a few days he is 
joined by a female, and to- 
gether they labor away un- 
til they have made a basin, 
or in some cases a ditch 
across the bed of the 
stream. Sow they fasten 
themselves with their 
mouths to stones at the up- 
per edge of this basin, and 
their bodies swing down- 
stream and sway in the cur- 
rent. 
Many hundreds of lam- 
preys have been actually 
counted on beds in the inlet 
in a single season by ob- 
servers at Cornell Univer- 
sity, and in 1891 Professor 
Gage saw there fully r,200. 
In these nests the eggs, 
after being fertilized, sink 
to the bottom and adhere 
firmly to the sand and 
stones, being covered by 
the lampreys stirring up 
the sand with their tails. 
After some days the eggs 
are hatched and the young 
lampreys, very much like 
small angle- worms, burrow 
into the sand. At first they 
live in the sand at the bot- 
tom of the nests, but soon 
make their way to the sand along the banks of the stream. Here they remain for 
perhaps two years or longer, with their eyes only rudimentary and their mouths 
valvular, feeding on very minute organisms that live in the mud and sand. 
It is said that the adult lampreys die soon after spawning, but this is not fully 
determined. It is also believed that some may return to the lake. When the young 
;'Q 
a 
'' o 
Mouth of lake lamprey ( Petromyzon n 
drawing by Mrs. S. H. Gage 
inus unicolor). Reproduced from 
E, eye ; S O, sense organs. 
