CHAPTER XXX 

 DEVELOPMENT OF THE BODY AFTER BIRTH 



1. INFANCY 



DURING infancy the body is nourished by fluids only, 

 chiefly by milk. As the formation of the first teeth is con- 

 nected with the ability to take up solid food, the period of 

 infancy extends from birth till the first dentition. 



(a) Circulation and respiration of the infant. Imme- 

 diately after birth the circulation in the umbilical vessels 

 ceases, and the umbilical cord constricts. If it is then cut, 

 no bleeding, as a rule, results, yet to prevent possible bleed- 

 ing it is ligatured and cut. Animals cut the umbilical cord 

 with their teeth. The part of the umbilical cord left attached 

 to the child dries up and falls off after a few days. The 

 navel discharges matter for some time and heals after 1214 

 days. 



Immediately after birth the first inspiration is made. The 

 alveoli of the lungs fill with air and their epithelial cells 

 become flattened. Simultaneously the blood streams more 

 abundantly through the vessels of the lungs. Gradually the 

 ductus arteriosus Botalli is obliterated and the septum 

 between the auricles is completed. The remains of the 

 umbilical arteries and veins degenerate to connective tissue. 



The rate of the pulse during the first week is 120140 per 

 minute; during the second year 1 10. The number of res- 

 pirations in the new-born is 44 per minute ; during the third 

 year 35-40. 



(b) Nutrition and growth of the infant. The normal 

 nourishment for the infant is the milk of the mother. The 

 replacement of this by other food (e.g. cow-milk or artificial 



327 



