276 PHYSIOLOGY CHAP. 



the upper half is nourished by blood which is more arterial and 

 richer in histogenic substances. 



When the placental circulation is suppressed, the umbilical scar 

 begins to form ; in the new-born child this scar is situated about 

 half way down the body (Bigeschi) or a few centimetres lower 

 down (Bongiovanni, De Billi, Belluzzi, a-nd Pilla), usually nearer 

 the pubic symphysis than the xyphisternum (Hecker). 



The lungs of the foetus at the ninth lunar month are fully 

 formed (Hertwig) ; after birth the size of the alveoli increases and 

 the cylindrical epithelium with which they are lined becomes 

 flattened owing to the distension. Whereas before birth the lungs 

 weigh 60 grms., those of the new-born child weigh about 90 grins., 

 the difference being due to the blood with which the capillary net- 

 work is filled (Gillis). The lung test of Daniel and Ploucquet 

 (1782) is based upon the increase in the volume of the lungs 

 caused by the distension of the alveoli with air. 



The heart of a new-born child weighs 15 grms. and, as in the case 

 of the quantity of blood, is greater in proportion to the weight of the 

 body than that of an adult. It beats at the rate of 120-140 a 

 minute, so that the whole circulation takes place in less time than 

 that of the adult, and the renewal of the blood in the capillaries 

 of the tissues is extremely rapid. 



The establishment of the cardio-pulmonary circulation brings 

 about other modifications in the composition of the blood and more 

 particularly in the structure of the corpuscles. According to 

 Kaibaud and Vernet (1904), the polynuclear neutrophile leucocytes 

 predominate in the first day of extra-uterine life, whilst during 

 the first year of life there is a physiological mononuclear leucocytosis. 

 The digestive system is adapted to the milk diet. The saliva 

 of the infant is scanty until teething begins, and has very little 

 action upon starch. The stomach has a very slightly developed 

 great curve ; it is almost vertical and possesses little tone in the 

 cardiac sphincter and thus regurgitation is facilitated. Its capacity 

 at birth varies from 25 to 30 c.c. according to the weight of 

 the body ; its secretion is small in quantity and contains very 

 little hydrochloric acid; it does, however, contain pepsin and 

 is capable of peptonising proteins (Keeve-Eamsay, 1908). 



The intestines are more highly developed in proportion to the 

 length of the body than those of the adult; the length of the 

 small intestine being 287 cm., that of the large 56 cm. The 

 meconium which has accumulated in the last section of the small 

 intestine and in the large bowel to the amount of some 75 grms. 

 at the time of birth is at once discharged by the infant. 



At birth the right lobe of the liver is far the most highly 

 developed; its weight varies, Hecker estimating it at 128 grms., 

 Gillis at 180 grms, and it bears to the weight of the body an 

 average ratio of 1 to 8. 



