SUMMARY OF BABY'S DEVELOPMENT
He discovers his hands at three or four months. At six months he sits alone, plays with simple objects, grasps for objects, and laughs aloud from the third to the fifth month. He says "goo goo" at four or five months. At one year he should stand with support, listen to a watch tick, follow moving objects, know his mother, play little games, such as rolling a ball, should have trebled his birth weight, and have at least six teeth, and should use three words in short sentences. At eighteen months he should say "mamma" spontaneously, walk and run without support, should have quite a vocabulary, should be able to perform small errands like "pick up the book," and should have twelve to sixteen teeth. At two years he should be interested in pictures, able to talk intelligently, and know where his eyes, nose, mouth, hands, and feet are. At three years, he should enumerate the objects in a picture, tell his surname, and repeat a sentence with six words.
In the case of a premature baby or a very delicate child, or as a result of a prolonged illness or a very severe sickness, such as spinal meningitis, the time of these mental and physical developments may all be postponed, while rickets, which will be spoken of later, is often the cause of late sitting, late standing, and late walking.