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



Plate CVII. 







Fig. 116. — Section of normal thyroid of adult female dojr. mother of dogs 13. 16. 17. 20. 21 and 22, ii.sed as control for 

 doK IS. figrure 117. Received same water but boiled before drinking. X16n, 







•n '..•. it. *?»!.•; >^iSd.'_i.- -• „- .. 



Fic. 117. — Section of markedly enlarged thyroid of adult dog IS. Result after five months drinking water in which 

 were suspended scrapings from fish troughs in which carcinoma of the thyroid in trout was continually developing. X160. 



