312 FIFTEENTH ANNUAL REPORT OF THE 



and they can easily be obtained for fish cultural purposes. The tullibee 

 and cisco are there also in enormous schools which spawn within a few 

 miles of the station. The yellow perch fingerlings run up in Frederick 

 creek as far as the lower stripping house dam in such dense masses as to 

 furnish some hundreds of thousands for filling applications annually. 



The Pleasant Valley station is still very seriously handicapped by the 

 outbreak of trout epidemics, due at present chiefly to the tumor disease, 

 which is apparently the same thing as that known to the German pathologists 

 as thyroid carcinoma. Unfortunately this disease is very widespread, 

 not only in the United States, but in countries very remote from one another. 

 It is not confined to one kind of trout, and extends also to some other fish, 

 for example, the whitefish. Mr. Davidson has recently observed it in 

 a large whitefish netted in Keuka lake. A great many brood fish have 

 been attacked by this tumor, and all of them in which the disease has been 

 noted have been destroyed. The contagion seems to arise from the large 

 spring pond, the only one of our properties which is not fully protected 

 against contamination from outside sources. This pond has been drained 

 and thoroughly cleaned. It will now be allowed to lie exposed to the weather 

 all winter, when it is hoped that the germs of the disease, of whatever 

 nature they may be, will be killed out. All ponds supplied by this spring 

 have been drained and will be left dry through the winter. We have no 

 knowledge of the cause of the tumor disease. It originates in countries 

 far apart, and in certain cases it appears as if the contamination must have 

 been carried with the eggs introduced from far away countries. In New 

 Zealand, for example, where certainly no fish ever were shipped, the disease 

 has become well-known in rainbow trout, Loch Leven and American brook 

 trout. It would seem, therefore, that the eggs contained the germs, or 

 else the germ exists in waters of various parts of the world and is ready to 

 attack the trout whenever conditions are favorable. 



The Pleasant Valley station now has three small artesian wells from 

 which water flows into the hatchery. The springs in the hatchery ground 

 on the side opposite the foreman's dwelling seem to be uncontaminated so 

 that the hatchery even now has enough good water to run ten or a dozen 

 troughs. Mr. Davidson is hatching about 300,000 brook trout eggs, besides 

 a lot of eggs of brown trout and rainbow trout. The hatchery, however, 



