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



Plate CV. 



^a'a '1^~P°S- 1", Hyperplasia of the thyroid at the end of five months, from drinking water in which were 

 do/6"fiCTre'^lT?'"^'Vl60^" troughs m which carcinoma of the thyroid was prevalent. The same expcrinietu as 



, ly^ 



'^. 



Fk;, 113 — Section of enlarged thyroid (m (nit; i^ m ^,. ..,., , 



ative changes in dog drinking water with mud from pond It). Craig Brook. 



