84 Thirtieth Annual Meeting 



1. A spot disease of tlie sac, appearing in the egg or after 

 liatc-liiiig. 



2. A disease appearing when the sac is about half absorbed, 

 characterized by a whitening of the sac, which begins in irregu- 

 lar white blotches: our most serious disease, known locally as 

 the "sac-epidemic :" attacking several species. 



3. Another disease of the sac stage, characterized by a 

 strong upward curvature of the trunk. 



4. A disease of the dorsal tin of a salmon in the first sum- 

 mer of its life, in which the fin is eaten away at its edges until 

 more than two-thirds gone and then heals up perfectly, with no 

 other apparent injury to the fish. 



5. A similar disease attacking the fins of young rain])ow 

 trout and steel heads, especially the caudal fin, which is com- 

 pletely eaten away, together with the adjacent fleslr until the 

 extremity of the back bone is bare. 



6. Fungus on the egg. 



7. Fungus on fry two to four months old. 



8. Fungus on adult salmon. 



9. Monstrous enlargement of the genital organs of salmon 

 in their secoiul yeaj'. 



1 0. Tn'matode parasites on young lake trout. 



11. \\\ epidemic attacking salmon two or three months old. 



12. An epidemic attacking salmon four or five months old. 



13. A sort of e})ilepsy in which salmon two or three months 

 old have temporarily lost their balance. 



One of the most interesting cases was that of the young lake 

 trout attacked hy ))arasites in 1896. These fish had been hatched 

 from eggs I'cceived from Northville and had apparently been 

 thriving until about the middle of July, wlien there was a slight 

 increase in the mortality. A week later the rate of mortality had 

 trchU'd and \)\ tlu' 10th of August it had increased more than 

 tenfold. At first it was thought possible that the mortality was 

 due to fungus, and the fish were treated with salt. No benefit 

 resulting, the microscope was brouglit into use and l)ehold the 

 fish were swarming with living, active parasites, which moved 

 about over the fish after the manner of loop-worms or leeches. 



