80 



PHYSIOLOGICAL KEGULATIONS 



tend to be similar to those just preceding and just following them. 

 Inversions in direction of change (accelerations and decelerations) 

 occur 11 times out of 29 possible ones (38 per cent). All changes 

 of rate are gradual; they too look as though a mechanical "gov- 

 ernor" exerted an inertia that prevented sudden fluctuations. Or, 

 whatever is concerned in exchanges exerts influences that tend to 

 be uniform and continuous. Trends endure for hours rather than 

 either for quarter-hours or for days. 



Comparing paths of water exchange, I find that ingestive ex- 

 change is less variable than urinary over periods of 24 hours, but 



Hours 



Fig. 46. Total water load (% of Bq) in relation to time in dogs nearly in water 

 balance. The number of tests is indicated in each series. Water was available to the 

 two dogs at all times except on dotted lines. A, one-fourth of daily food was eaten at 

 zero time. B, one-twenty-fourth of daily food was eaten every hour. C, one-eighth of 

 daily food was eaten at and at 3 hours. D and D, control regime = no food or heat. 

 E, heated by radiator during third 1.0-hour. F, no food or water for four hours, then 

 presented with water. G, heated during first 1.0-hour (no water), then presented with 

 water. New data of Eobinson and Adolph. 



in periods of 1 hour and 0.25 hour is much more variable (CA ± 75, 

 ± 180) as ascertained in tests of the sort shown in figure 46. Evap- 

 orative exchange varies about as much as urinary, within each of 

 the time intervals mentioned. 



Each of the quantities concerned in water intake (table 1), and 

 in water output, is equally capable of evaluation by its variations. 

 In the end I would learn precisely which are the more uniform 

 processes and which less uniform in the handling of water by the 

 dog, and what periodicities are characteristic of each. 



Adjustment of water content is hy means of the exchanges rep- 

 resented in the fluctuations that are being studied. Content is a 



