in i i ii n emu \\i> r \i; \ i in ROID 0LA1 



"".1 



and ii can I'" produced in certain normal animals (particularly rats) by 

 placing them on an excessive meal diet. Importanl observations bearing on 



this point have I M made by Marine on brook trout, in which it has i 



found thai ili«' so-called carci aa thai develops when the fish kept in 



hatcheries are fed with unsuitable food and overcrowded, is really a 

 typical hyperplasia. In its second stage this develops into what is known 



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193 Mi • thyroid gland of dog, .1. normal; B lloid 



From .V .1 L,enhai I 



as colloid goiter which is produced by a deposition of colloid material 

 between the rows of cells so as to cause an opening oul again of the 

 vesicles (Fig. 193 . with a consequent tendency to a reversion to the 

 normal histological structure, so far ;is this is possible. The vesicles in 

 such a gland are of enormous Bize, and the lining epithelium, low cubical, 

 or almost flat in shape. 

 The outstanding characteristic feature of th Moid material is that 



