Renal Functiop in the New-BornThe glomeruli are all formed in the new-born infant but they are much smaller and

more crowded together than in the adult, and the remainder in the nephron is..undeveloped.) The glomerular capsule which covers the tuft of capillaries consists of tall columnar cells in foetal life,- of cubical cells in the new-born and of flattened cells in the adult ; it is probable that the greater thickness of the glomerular membrane accounts for the relatively

low glomerular filtration rates found in early life.,

That regulation of the internal environment is carried on in utero chiefly_by thep acetit'a .4 indicated by the fact that apparently normal children may be born with v o t : . •f cipOiites's kidneys. The steady rise of ticil'and uric acid in the liquor amnii during regriancy ,stiggests that tIe,kidneys normally begin to function before birth, although only Ito a small. extend. The u'riiie'bt babies immediately after birth is generally acid with a small amount of urea and a low osmotic pressure ; albuminuria is not uncommon in the first five days of extra-uterine life.

Immediately after birth' the body becomes dependent on the kidney for elimination of nitrogenous end - products of metabolism and to a large extent also for regulation of its internal environment: The plasma protein level is low in infancy and, thereforeGthe colloid osmotic pressure of the plasma is lower than in the adult; a fact which favours the filtration of fluid through the glomerular capillaries as well as through capillaries in all parts of the 190e,,,\The resulting tendency to accumulation of extracellular fluid and development of dedem, however, offset by the low fluid intake which occurs during the first few days of extra-uterine life, annhe volume, of the extracellular uid actually tends to fall ; at the time the blood urea concentration rises. In a few days, as the fluid intake increases, the extracellular fluid volume rises and the blood urea falls. ;

(c7 In babies a few days old glomerular filtration rates measured by inulin clearance are about 30 ml/sq.th/min compared with about 75 ml/sq.m/min in the adult. Tubular function is also much less efiicied than in adultS. Urea clearances are also low in infancy. All these values increase to adult level towards the enc1of the first year.

In new-born children the volume of urine passed per day is of the order of 20 ml and this increases only when the intake of fluid becomes greater as the maternal milk supply improves. Water given to babies up to three months of age is excreted very slowly and this is true of

other new-born mammals. The specific gravity and osmotic pressure of the urine are low. . \ ; .