WATER RELATIONS OF FROG 117 



cant, for weighings repeated at 2-minute intervals differ by only 

 CA ± 0.07. Water intake in successive periods of 1 hour varies by 

 CA ± 32.3 per cent of the mean intake (45 observations). Water 

 output in 1-hour intervals is believed to vary by about the same 

 coefficient ; but exact data have not yet been obtained in successive 

 periods. 



While successive hourly periods show differences of intake aver- 

 aging 32.3 (CA), these same rates deviate from the mean rates of 

 each individual by 31.1 (C.V.). In a random series CA equals C.V., 

 as here ; hence a high rate does not tend to follow a low one, nor vice 

 versa. If there were trends lasting more than one hour, C.V. would 

 tend to exceed CA. 



In the initial stages of recovery, the water intakes being aug- 

 mented as much as eight fold, the variation among the rates (C.V. 

 ± 27) is almost equal to that in turnover (± 31.1). This suggests 

 that relative variability overrides whatever absolute variability 

 may be present. Or, the reproducibility of the rate is proportional 

 to the amount of water being handled as intake. 



Variability of content in water balance may be considered in 

 relation to mean rate of turnover. In one hour 1.66% of Bq is 

 on the average taken in and put out again. The standard differ- 

 ence of successive hourly weights (±0.77%) is 46 per cent of 

 this ; and the mean difference is 37 per cent, mean difference being 

 0.798 X standard difference. In 24 hours the turnover is 40% of 

 Bo, while the coefficient of difference (± 2.22%) in 24-hour inter- 

 vals is only 6 per cent of the turnover. "Precision" as computed 

 by the method of Gasnier and Mayer ( '39) is therefore 95 per cent 

 in 24 hours but only 63 per cent in 1 hour. 



The variation of intake (32.3 CA) might correspond to an inac- 

 curacy of ± 0.54% of Bo each hour. This alone almost covers the 

 variation in body weight (± 0.77% of Bo). Similarly the variation 

 among individuals of output alone (± 23.5 C.V.) is a factor in the 

 content. The variation of content may be viewed as an interplay 

 of both these variations of exchange ; a dded together , the most usual 

 fluctuation of intake would be 1.66 X V 32.3^ + 23.5 VIOO or ± 0.65% 

 of Bq. The value 0.65 being less than the value 0.77 there is no 

 significant evidence of mutual compensation, in one-hour periods, 

 between intake and output. Most compensations occur over longer 

 periods of time, but within less than 24 hours. 



