Bull. U. S. B. F. 1912. 



Plate XCVII. 



Fig. 96. — Marked hyperplasia domesticated brook trout used as control for figure 97. Fish 1040, table ix. X86. 



Fig. 97. — Fish from same lot treated by adding in continuous concentration potassium iodide in the water 1 : 5,000,000. 

 Marked regression of h>perplasia at the end of 13 days. Fish 1039, table ix. XS6. 



