WATER EXCHANGES OF DOG 



19 



other substances lost and gained are small in comparison to water 

 and are known to be almost independent of water content. 



In each actual test a dog unfed for 16 hours but allowed water 

 ad libitum is given water by stomach tube (at zero time). Urine 

 is collected, and body weight is measured, every 0.25 hour. In plan 

 the test requires little apparatus, for all measurements are made 

 with a graduated cylinder, a sensitive balance, and a clock. In 



12 3 



Hours 

 Fig. 1. Course of total water load (per cent of the body weight, Bo, at zero time) 

 after diverse single quantities of water are given by stomach tube. Dog, four individuals. 

 The number of tests indicated is also the number of measurements averaged for each 

 point. In series A the initial water load was 6.14 per cent of Bq. New data of Kingsley 

 and Adolph. 



practice each dog needs to be trained to stand still during several 

 hours, to take a stomach tube without struggling, and to submit to 

 continuous observation. Previously a bladder fistula or an exteri- 

 orization of the urinary bladder is surgically produced. Ulti- 

 mately many computations are required to place the results in 

 coordinated and comparable form. 



