Bull. U. S. B. F. 19 12. 



Platk LXII 



Fig. 17. — Wild brook trout from .\u Sable River: 8.2 cm. Ions: cross section shou-iiiE distribution of normal thyroid. XS6. 



'•"^40 j^-^, -■*^' djl^^^s^'^"' '*'' 





■'^rj2»'-' 



Fic. 18. — Algonquin wild brook trout; simple hyperplasia: high cuboidal epithelium reduction in some follicles and 

 absence in others of colloid. Distinct hyperaemia about follicles: increased amount of thyroid. XS6. 



