INFLUENCE OF DIET AND IODIDES OPOSSUMS 65 



suggests that the hyperplasia is due to the protein fraction of the 

 food, but further experiments are necessary to estabUsh this fact. 

 These experiments show that the spontaneous hyperplasia ob- 

 served in the thyroid gland of the opossum under laboratory 

 conditions can be produced and controlled by diet alone, and 

 that given the conditions dietary and otherwise which produce 

 an ^tive hyperplasia iodine will not inhibit the reaction. At all 

 periods of the hyperplasia and to an extent which is proportional 

 inversely to the rate of hyperplasia iodides will cause the storage 

 of intrafollicular colloid. The experiments also emphasize the 

 necessity in studies on the reactions of the thyroid gland, of con- 

 trolling closely the conditions under which the animals are kept, 

 and of reducing the gland as far as possible by diet and iodides 

 to a normal base before the experiments are begun. 



