316 Kojima 



If the thyroid feeding is continued over a long period (a month), most 

 of the alveolar cells are again found to have become of the ordinary size — 

 although a certain number of small cells may still be seen — and zymogen 

 granules are again accumulated within the cells. 



The mitotic figures in the pancreas do not begin to appear until after 

 three days' feeding; after seven days' feeding they become fewer in 

 number and graduall}^ disappear. They are still visible after three days' 

 intermission, following four days' feeding, but after a week's intermission 

 are no longer visible. The mitotic figures are seen after fresh thyroid, 

 dry thyroid, and boiled thyroid extract : also after feeding with the 

 residue of the thyroid after a decoction has been made and filtered off. 

 It follows therefore that the autacoid substance which excites changes 

 in the pancreas resists the temperature of boiling water, and that it partly 

 passes ofi" into the water. It is, however, entirely insoluble in alcohol and 

 ether, extracts made with these fiuids producing no eft'ect. 



Thyroid feeding also produces certain changes in the size and structure 

 of the nuclei and in the staining properties of the nucleoli, which are 

 described in the body of the paper. 



Another change which is produced is the formation of very distinct 

 vacuoles within the cytoplasm ; this vacuolation is not, however, general, 

 but occurs in patches within the gland. Small vacuoles are occasionally 

 to be seen in the normal rat's pancreas, but those which are here referred 

 to are large and conspicuous, and may occupy a great portion of the cell, 

 displacing the nucleus towards the basement membrane. Here and there 

 a communication can be made out between the vacuoles and the lumen of 

 the alveolus.^ 



No appreciable change can be made out in the cells of the islets of 

 Langerhans nor in the centro-acinar cells. 



Effects of Castration. 



The effects of castration upon the pancreas have also been investigated ; 

 the results have been negative. Previous castration does not affect the 

 results of thyroid feeding. 



Effects of Iodides and other Salts upon the Pancreas. 



A further part of the investigation was directed to determining 

 whether other combinations of iodine than that contained within the 

 thyroid would produce similar effects upon the pancreas. With this object 

 a combination of iodine and protein, sold under the name of iodo-protein, 

 was compared with a commercial preparation obtained from the thyroid 

 gland. The former was found to be ineffective, the latter effective. On 

 testing the eff'ect of administering certain salts, especially the salts of iodine, 



1 Vacuoles have previously been described in the alveolar cells of the dog's pancreas as 

 the result of vagus stimulation (Babkin, Rubaschkin, and Ssawitsch (13)). 



