vii THE STAGES OF LIFE AND DEATH 275 



tion (Fig. 116). It advances from behind forward along the 

 left face of the inter-auricular septum, extending at birth with its 

 anterior free border beyomi the circumference of the foramen 

 ovale. When the pressure in the left auricle increases, the valve 

 is distended and applied to the orifice of the foramen, and finally 

 closes it up. The whole of the blood of the right auricle coining 

 from the two venae cavae must then pass into the right ventricle 

 below, and the third, or cardio-pulmonary circulation, is thus 

 definitely established. 



The umbilical arteries in the interior of the body are obliterated 

 as far as the sides of the bladder between the fifteenth and the 

 twentieth day, after contraction within their sheaths, and are 

 finally transformed into the lateral ligaments of the bladder. A 

 similar change occurs in the ductus Arantii, which becomes the 

 ligamentum teres of the liver. 



The normal foetus at the end of pregnancy weighs, as we have 

 already seen, on an average 3200 grms. and measures about 50 cm. 

 in length. During the first three days after birth it loses about 

 250 grms. in weight, but regains its original weight between the 

 tenth and the fifteenth day. 



Even within physiological limits there are many circumstances 

 which influence the weight and length of the foetus : amongst 

 others the bodily development of the father (La Torre) ; the age 

 and bodily development, more especially of the pelvis, of the 

 mother (Fasola and Bertazzoli) ; multiparity ; and the sex of the 

 foetus, the males being longer and heavier. 



There also seems to be a direct relation between the quantity 

 of the amniotic fluid, the length of the cord, the weight of the 

 placenta, and the weight of the foetus (Zentler, Smith). Duncan 

 considers that the weight of the new-born infant increases with 

 the age of the mother up to the 29th year, and the length up to 

 the 44th year. According to Wernich, the children borne by a 

 woman who menstruated early are, ceteris paribus, heavier than 

 those borne by one who menstruated late. Cuzzi found that the 

 weight of the child increased with the duration of the menstrual 

 haemorrhage of the mother ; according to Hecker, in the case of 

 successive pregnancies the bodily development of each offspring is 

 superior to that of its predecessors, although, as was pointed out 

 by Wernich, this rule does not hold when the intervals between 

 one pregnancy and the next are either too short or too long. From 

 these observations a corollary of practical value may be deduced, 

 since the size of the foetal head depends, within certain limits, on 

 the weight and length of the foetus (Ahlfeld, Budin, Kibemont). 



We will pass over the minute external characteristics by which 

 the maturity of the new-born child may be estimated, merely 

 bearing in mind that the upper half of the infant is always better 

 developed than the lower, because as we have already remarked 



