Bill U. S. B. F. 191 2. 



Plate CI II. 



Fi<;. IHS — Section lliroiiKli tumor uf two-ye;ir old brook trout treated with bichloride ot mercury added by continuous 

 flow to the water in proportion of l:5.tH)().()iin. Result at the end of 11 days, fireat reduction in size of tumor. Reversion 

 of tnnior tissue to the norma 1 t.\ pe. Fish 1144. table xii. XS6. 







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M:<:sS^:^^;^ 



Fig los) — Domesticated brook irovit. Visible tvimor. Marked diminution in size of the tumor and marked cIi.anKe in 

 tumor tissue with reversion toward normal, as the result of treating for .'2 days with arsenic tnoxide added by continuous 

 flow to the water. Xote marked change in epithelium. Fish 2036. table xiv. X86. 



