Studies on the Eiidocriue 11 lands 273 



days after the thyroid feedini,' had been stopped, and one animal of A group 

 died on April 1, i.e. after seven days' thyroid feeding, apparently from 

 diarrhoea. Its weight was only 140 grm. the day before death, although 

 at the commencement of the thyroid feeding it was 1(15 grm. In this 

 animal the large inte.stine was greatly congested and the contents were 

 watery. A second rat belonging to A group died on April 3, i.e. after 

 thyroid feeding had been replaced during two days by parathyroid, so that 

 only one rat of A group was left for further observations. 



At the end of the week of parathyroid feeding one rat (No. 3) of each 

 group was sacrificed and the pancreas examined ^ 



(a) In Unoperated Animal. 



No. 3 rat of group A. Parathyroid-fed (after thyroid). Weight 

 165 grm. Unoperated. Nothing noticeable post-mortem. 



Pancreas. — In most parts the alveoli are about e(|ual in size to 

 those of No. 1 animal of A group (normal). There are a certain 

 number of small cells, but most are fairly uniform in size. The cell- 

 nuclei vary in size from 3-7m to d/j. ; the majority are between 5^ and 

 6-2/uL. Many contain a distinct nucleolus; others merely coarse 

 chromatin granules. Both nuclei and nucleoli are stained blue by 

 Mallory. No mitotic figures are visible, nor are any vacuoles observ- 

 able in the cytoplasm. Zymogen granules are plentiful : many more 

 than immediately after thyroid feeding. They are, as usual, specially 

 abundant in the alveoli adjacent to the islets. The islets show no 

 change. 



(b) In Parathyroidectomised Rat. 



No. 3 rat of group B. Parathyroidectomised forty-nine days before 

 death. Parathyroid-fed (after thyroid). Weight 206 grm. Nothing 

 noticeable post-mortem. 



Pancrea.s. — Although there are many small alveolar cells, mosi 

 are moderately large and nearly equal in size : this also obtains for 

 the alveoli. The nuclei vary from o/ut. to 9/x, most being between 

 5^c and 6-2/ul. Nucleoli are distinct in many of the nuclei, and the 

 tendency of the chromatin granules to be arranged at the periphery 

 of these nuclei is observable : other nuclei have coarse chromatin 

 granules without any clear differentiation of nucleoli. No mitoses 

 are to be found, and there is not much vacuolation of the cytoplasm. 

 Zymogen granules are decidedly more abundant than in the rats 

 killed immediately after thyroid feeding. The zymogen is, as usual, 

 specially marked in the cells adjacent to the islets. The islets them- 

 selves show no change. 



1 It must be borne in niinfl that all these animals, which were now fed with addition 

 of parathyroid, had previously received thyroid with their food, and the effects of the 

 thyroid feeding may not have entirely passed oft'. 



