270 



PHYSIOLOGICAL EEGULATIONS 



urinary water output in ordinary water balance, and (d) maximal 

 water output in water diuresis (fig. 139). Large numbers of 

 measurements have gone into the determinations of means or 

 maxima in each category. In a previous chapter these values of 

 rates of water exchange are considered as species differences with- 

 out reference to body size. Here they are found to be related with 

 body weight according to allometric equations. 



The conclusions indicated among mammalian species are: {!) 



Total intake is roughly proportional to B°-^. (2) Maximal intake 



+4 



CP 



+3 



D 



-P 



C 



V- 



O 



:5 



M- 

 o 



Q) 

 -P 

 O 



cc 



o 



+2- 



+1 - 







I 2 3 4 5 6 7 



L09 Gm. Body Weight 



Fig. 138. Eate of total water intake in relation to body weight among diverse 

 species of mammals. Lower line, mean turnover rates in control conditions (from table 

 20): Eto = 0.010 Bo-88. Upper line, maximal rates after injuries of hypophysis (from 

 table 13): E„„ = 0.033 Bo.97. 



is nearly proportional to B^° (Eichter, '38). (5) Ordinary urinary 

 output is proportional to B°^ (4) Maximal urinary output is 

 nearly proportional to B°-®. (5) The ratio of ordinary total intake 

 (or equal output) to urinary output, ranges from 2 for small spe- 

 cies to 5 for large ones. {6) The maximal urinary rates equal 32 

 to 20 times the ordinary rates, the augmentation ratio being less in 

 small animals which have turnovers already large in proportion to 

 body weight. (7) Maximal intakes after hypophysial injuries, and 

 maximal outputs after water ingestion are nearly equal. (8) 



