CARCINOMA OF THE THYROID IN SAI^MONOID FISHES. 419 



WASHINGTON. 



Baker Lake. — Limestones and schists to the south and volcanic rocks to the north and west. Age 

 unknown. 



Birdsview. — Schists partly ferruginous. Age unknown. 

 Little White Salmon River. — Basalt. Late Tertiary age. 

 Big White Salmon. — Basalt. Late Tertiary age. 



WEST VIRGINIA. 



White Sulphur Springs. — Romney shale. Devonian ^ge. 



WISCONSIN. 



Bayfield. — Lake Superior sandstone, Cambrian age, deeply buried under glacial lake clay. Quater 

 nary age . 



Madison. — Madison sandstone, Cambrian age, under heavy cover of glacial gravel. 



CHEMISTRY OF THE WATER SUPPLIES. 



There are no very definite chemical standards by which the fish-cultural value of a 

 water may be predetermined without the test of experience with fishes. The ordinary 

 sanitary analysis is of almost no value, the showing with respect to dissolved air gases, 

 which are of primary importance in fish culture, being usually omitted. As for a mineral 

 analysis, it is difiicult to interpret it in fish-cultural terms since fishes thrive in waters 

 of such varied chemical content that conclusions can not be drawn from a statement of 

 the inorganic materials dissolved, unless they show the water to be so heavily mineral- 

 ized that it is no longer fresh, or unless it contains the metals known to be highly poison- 

 ous to fishes. Even in the latter case special determinations must be made and large 

 quantities of water used, since some metals, for instance, mercury and copper, are fatal 

 to salmonoids in dilutions far beyond detection in ordinary routine mineral analysis. 



In order to lay a foundation for the possible estabhshment of fish-cultural standards 

 in water analysis, by long fish-cultural experience with waters whose chemical consti- 

 tution was determined, the Bureau of Fisheries has had analyses made of many waters 

 used to supply its various stations for the propagation of fish throughout the country. 

 These analyses have been made by the Bureau of Chemistry, Department of Agriculture. 

 Since not all these stations engaged in trout propagation whose water supplies have been 

 examined chemically have been thoroughly investigated to determine their status with 

 respect to thyroid disease, it is not possible to divide them into those which are subject 

 to and those which are free from the disease, if, indeed, there are any belonging unequivo- 

 cally to the latter class. We have therefore shown only the results (table ti) for waters 

 supplying such stations as are known to have the trout thyroid disease endemic, save 

 the last two (no. 11737 and 11 738), which supply the State hatchery at Cold Spring 

 Harbor, N. Y., and one of which appears to be at present free from the disease. By a 

 scrutiny of the mineral content of this water at the latter station, nothing distinctive 

 is to be found. It is low in total solids and therefore very lightly mineralized; the 

 chlorids, sulphates, silicates, and bicarbonates of the common earth metals make up the 

 bulk of the residue. These statements apply equally to many of the waters in which 



