Studies on the Endocrine CJlands 357 



the nitrofjen retention does not show any marked diminution durin*; the 

 week foUowini; the operation, but it afterwards decreases considerably 

 more than in the other jjroups. During; the meat and rusk feedintr a 

 larger amount of nitroiren was taken in as food, but less was retained in 

 the body. Durinrj the thyroid feedintj the retention of nitrogen was far 

 less in all the groups, but during the period which followed, in which the 

 thyroid was omitted and parathyroid substituted, the amount of nitrogen 

 again increased (C.'hart 4). 



Calcium. — During the first week of feeding with melox the amount of 

 calcium taken in was far greater than when meat and rusks or when rusks 

 alone were used as food. This is accounted for by the fact that melox 

 contains many small pieces of bone, and consetjuently far more calcium 

 than the rusks or meat.^ On substituting lean meat and rusks or rusks 

 alone for the melox, the calcium contained in the food was therefore 

 greatly diminished (Chart 5). 



With regard to the amount of calcium in the urine, it may be stated 

 that there is always some daily variation in all animals. But although a 

 diet of rusks or of meat and rusks contains so much smaller an amount of 

 calcium than does melox, nevertheless there was no more calcium in the 

 urine with the melox feeding than with the other diets. In B group 

 (parathyroidectomy) the amount of calcium gradually increased, whereas 

 in C group (thyroidectomy) it diminished (Chart G). 



With regard to the retention of calcium in the body, it is noteworthy 

 that no differential change is apparent as the result of thyroid feeding, a 

 diminished retention occurring in all the groups. During the following 

 week (parathyroid feeding) the amount again increased to its normal level 

 (Chart 7 ), but again it is not easy to decide whether the increase of calcium 

 retention was due to parathyroid feeding or to cessation of thyroid 

 feeding. 



Second Series. — In this series of experiments three full-grown male 

 and three full-grown female (non-pregnant) rats were employed. The sexes 

 were kept in separate metabolism cages. From May 5 to May 11 they 

 were fed with ru.sk-paste alone. From May 12 to May 18, 01 grm. of dry 

 ox-parathyroid per rat per diem was added to the food. From May 19 

 to May 25 they were again fed with rusk-paste alone. From May 26 to 

 January 1, 3 grm. of fresh sheep-thyroid per rat per diem was added to 

 the diet. 



During thyroid feeding the body- weight and appetite decreased, whilst 

 during parathyroid feeding there was no marked change. During the 

 parathyroid feeding the amount of food consumed by the females in- 

 creased, while that of the males decreased. After the parathj^roid feeding 

 had ceased there was a remarkable increase in the amount consumed in 



1 It must, however, be stated that most of the bony fragments in the groimd melox 

 were rejected by the rats, so that the whole of the calcium in that diet was not ingested. 

 It was partly on this account that it was discontinued and a meat and rusk diet substituted. 



