440 BUI.LETIN OF THE BUREAU OP FISHERIES. 



ber II. The stream was therefore seined and 48 fish were caught and examined. Of 

 these 3 1 were found to have visible tumors, many of large size. 



Pond 1 5 had been the receptacle for affected fish taken from the different troughs, 

 tanks, and ponds. There were approximately 450 fish in this pond; 164 of these are 

 recorded as dying during the course of the summer. At the end of September the 

 remainder, all of which still had visible tumors, were killed; the record states 276 in all. 



The conditions for observation at the Bath hatchery during the summer of 1909 were 

 unfavorable owing to lack of records as to the origin of many lots of fish, to inadequate 

 help, preventing frequent examination of the various lots, and to frequent changes of the 

 various lots from pond to pond, due to the exigencies of fish culture. The most important 

 observations made were the marked degree to which the water of the big pond and the 

 tanks it supplied were involved in the epidemic; the striking evidences of immunity in 

 the adult rainbow and brown trout from the Caledonia hatchery; the fact that the 

 yearling brook trout exposed to the disease in pond 11 continued to develop it rapidly 

 although transferred to trough 18, in which nevertheless the Cold Spring Harbor yearling 

 brook trout in trough i6, which was supplied by the same source, springs C and F, 

 remained free from the disease during ttie summer; and the lack of evidence of spon- 

 taneous recovery in the 2-year-old brook trout living under conditions of partial freedom 

 without artificial feeding during the summer in the brook; the high incidence of the 

 disease in the large pond, A, where the flow of water and proportionately great area 

 of the pond produced conditions much more favorable from this standpoint than are 

 usual under conditions of domestication; and the rapidity of involvement of the fish 

 by the disease and the great number affected. 



As the main activities of this research were, in 1909, transferred to the Craig Brook 

 station in Maine, no further observations were made at the Bath hatchery during 1910 

 and 1911, but in the middle of October, 1912, for the purpose of determining what the 

 condition of this hatchery might then be, an inspection, covering one day, was made. 

 No essential changes have been made in the water supply or other arrangements of 

 the hatchery other than those already described. The hatchery now carries a stock 

 of about 3,000 brook trout hatched in the spring of 191 1. With the idea that fish 

 hatched from the eggs of wild fish might prove more resistant to the unfavorable con- 

 ditions in this hatchery, eggs were obtained from the Ontario Fish and Game Commis- 

 sion in Canada. Approximately 1,500 fish were hatched from these eggs and main- 

 tained in a separate trough. The remaining i ,500 fish were hatched from eggs obtained 

 from a private hatchery in Massachusetts, and were also kept in a separate pond. Both 

 these lots of fish showed well-developed examples of the disease ranging from the first 

 evidence of red floor to protruding tumors of 7 to 10 millimeters. Of the 1,500 fish 

 hatched from the wild-fish eggs, some 200 were examined, 9 of which were visibly affected, 

 and 200 examined from the lot of 1,500 hatched from the eggs from the Massachusetts 

 hatchery showed 12 diseased fish. From this inspection it is evident that the disease 

 is still endemic at the Bath hatchery. 



