Studies on the Endocrine Glands 257 



although varyintj somewhat in size. For certain experiments other animals 

 <dogs, cats, rabbits, guinea-pigs, fowls) were employed. 



Diet and Treatment. 



Animals of about the same size, and generally of the same sex, were 

 chosen and fed ;id libitum with a diet of fixed and known composition 

 for a week or more. They were weighed at frefjuent intervals. Only 

 those that showed during this preliminary period no marked diH'erence in 

 weight were employed for the actual experiment. The food used for dogs 

 and cats was meat, oatmeal porridge and milk : for guinea-pigs, rabbits, and 

 hens — oats, cabba<;es, and Indian corn. As the standard food of the rats 

 rusks' were eventually chosen. They were ground in a small mill, and 

 about 40 per cent, water was mixed with the powder so as to make it into 

 a soft paste. The composition of the rusks was as follows : — 



Protein . . . . .1811 



Gluco.se ..... 2 -98 



Fat . . . . (iO.S 



Cane sucjar ..... 4"o2 



Calcium ..... 005 



Starch. ..... 48-92 



Water ...... 635 



Ash . . . 3-86 

 Dried residue, obtained after filtering ofi' 

 the oflucose which had been obtained in 



carrying out the estimation of starch . 8*58 



10000 



It will be observed that this furnishes a diet wnth the food-stufis in 

 suitable proportions. Other foods which were at first tried were found to 

 be too variable in composition or otherwise unsuitable. Additional water 

 was offered to all the animals once or twice every day, but as a general 

 rule it was found that the rats had a sufficient amount in the paste 

 supplied to them. 



For investigating the efi[ects of operation or diet upon their metabolism 

 the rats were kept — in groups — in the small wire metabolism cages de- 

 scribed by Profes.sor Schafer (Quart. Journ. Exper. Physiol., 1912, 

 vol. V. p. 204). Occasional COg estimations were made in certain of the 

 experiments. The effects upon metabolism were not investigated in the 

 other animals employed. 



Operative Procedures. 



Upon some of the animals certain operations were performed, 

 (a) Thyroidectomy. — After being anaesthetised with ether, sometimes 

 combined with chloroform, a median incision was made over the upper part 



1 Those made by Habbard of Glasgow. 



