6 E. F. Adolph 



meniscus from minute to minute as urine collects in it (Hoy 

 and Adolph, 1956). Quantitative collections can also be made 

 without the cannula, at the urinary papilla or by bladder 

 puncture; during rapid urine flows these collections give the 

 same results as with the cannula (Heller, 1947; McCance and 

 Wilkinson, 1947; Falk, 1955). 



Water excess, administered by stomach tube, gives rise to 

 very little diuresis at birth (Fig. 4). In the course of several 



Fig. 4. Water diuresis at various ages in infant rats. Points 

 show mean and standard error at end of each period of urine 

 collection. DA = days after conception. From Falk (1955). 



days the rat's response increases, until at about ten days 

 after birth the response per unit of body weight is of adult 

 size. The ages indicated on the graphs shown here are 

 reckoned from conception instead of from birth, the average 

 gestation time for rats being 21*3 days. Actually in human 

 infants the maturation of the diuresis was found by Ames 

 (1953) to be triggered by birth rather than by scheduled age, 

 since prematures acquired the diuretic response about as soon 

 after birth as postmatures did. 



A familiar notion about the way in which water diuresis is 

 excited is to suppose that the neurohypophysis withholds its 



