58 R. R. BENSLEY 



mary or contributing etiological factors in this condition, the 

 work of Reid Hunt ('11), Chalmers Watson ('05), Missoroli ('13) 

 and Marine ('14) on the relations of diet to hyperplasia in white 

 rats and mice, and in the brook trout, and the potency of iodides 

 in procuring reversion of hyperplastic glands to normal and in 

 preventing hyperplasia demonstrated in many papers by Ma- 

 rine and his associates, pointed to diet and iodides as a subject 

 for primary investigation. 



In the former series of experiments the animals were kept con- 

 fined in cages, and were fed on table scraps from the restaurant, 

 that is to say on cooked food, containing abundance of meat, 

 eggs, bread, etc. The animals under these conditions showed a 

 pronounced preference for the meat and eggs. The food was re- 

 newed daily. Under these conditions the animals increased in 

 weight rapidly, often in the course of three weeks nearly doubling 

 their weights. 



In the series of experiments which are reported in this paper, 

 one animal of each group of experiments, was carried on the diet 

 indicated above to see if the hyperplasia was produced and in 

 what degree. The results as regards these controls are col- 

 lected into table one. The remaining animals were divided into 

 four groups, of which one group of two animals was used to de- 

 termine whether iodides would revert the hyperplastic glands to 

 a normal colloid type. A second group of three animals was 

 kept under the same conditions as the controls except for the 

 fact that they received from the day of their entry into the 

 laboratory daily two drops of iodide of iron, to test whether 

 iodine would inhibit the hyperplasia, if the factors producing it 

 were present. A third group of eight animals was kept on 

 dietaries designed to maintain them at nearly constant weight, 

 and the fourth group of five animals was employed to test whether 

 increasing the meat component of the diet would increase the 

 reaction. 



In every case, at the end of the experimental period, the ani- 

 mal was killed by bleeding from the femoral artery. The thyroid 

 glands were removed as rapidly as possible and weighed, then 

 'Axed in formalin Zenker, and acetic osmic bichromate. 



