Bull. U. S. B. F. 191 2. 











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Fig. 114. — Section of thyroid of dog 2U used as control for dogs 22. 16 and 17. Received the .'^anie water asdogs lb. 17 

 nnd 22. but. like control dog 21. boiled before drinking. X16CJ. 



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Kui 115. — Dog 22, Section of enl:ir^.ed thyroid. Well developed hyperplasia after drinking water five months with 

 I : e ?._(•-_.._. .- , . . "Xh^ same experiment and result as dog 16. figure 111. and dog 17, 



suspended scrapings from infected fish troughs, 

 figure 112. X160 



