BULL. U. S. B. F. 1912. 



s .r% 





Fu;. 114. Section of thyroid of dog 20 used as control for dogs 22. 16 and 17. Received the same water as dogs 16, 17 

 and 22, but. like control dog 21, boiled before drinking. X160. 



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*******'? M** 



Fu: 115. -Dog 22. Section of enlarged thyroid. Well developed hyperplasia after drinking water five months with 

 suspended scrapings from infected fish troughs. The same experiment and result as dog 16. figure 111. and dog 17, 

 figure 112. X160. 



