PERCENT TROUGHS INFECTED-CUMULATIVE 

 _ N> Oi -P> c 5? 



o o o o o o 



1111 



o 



z 

 n 



en 



o 



Ol- 



c_ 



c 



Oi 



Fig. 9. — Epidemic at Leavenworth hatchery - 1953. Curve represents the total 



nunber of troughs in which there were infected fiah at the indicated dates, 



31 



