It may be well to mention here that children will often remain, for a considerable time, almost stationary in height, and then have periods of very rapid growth. The latter is often to be observed in the ninth or tenth year, and again at the approach of puberty. Variations in weight-gain are also often to be observed; these seem to hold a definite relation to the fluctuations in the rapidity of height-increase.

Besides these points, which are the most reliable evidences of the proper progress of development, there are certain features that appeal more directly to the notice of parents, and on this account deserve consideration. The age at which a child sits erect, at which it creeps, walks or talks, are instances of the class of features referred to.

The head can usually be held erect by the end of the third month and the body maintained in the sitting posture a month later. By the sixth month the infant can sit up with ease, accomplish many movements with the arms, hands and fingers, and enjoy playthings. At the eighth month he may be able to creep; by the ninth or tenth, to drag himself upon his feet with the assistance of his hands and arms and some artificial support; by the eleventh, to walk with assistance; by the fourteenth, to walk alone, and by the eighteenth, to run.

At eight months an infant will imitate sounds and articulate several syllables; at ten, can often speak one or two words, and after twelve months is able to join several words together.

The anterior fontanelle should be completely closed at some period between the fifteenth and twentieth months.

Tears begin to be secreted during the third or fourth month, and saliva, between the fifth and sixth.

After birth both hair and eyes often change color as age advances. When an alteration takes place in the eyes - which are quite commonly blue or blue-gray in the new-born - it begins about the sixth or eighth week and may be to either a lighter or darker hue. Changes in the hair begin later, the tendency always being to darken, and the most marked alteration occurring between the seventh and fourteenth years.

Examples of Variations in Disease. - If on being measured and weighed, a child be found to fall short of the normal standard for its age, and if, at the same time, there be a want of plumpness of body, roundness of limb, and firmness of flesh, the existence of some fault in diet or in the digestion and absorption of food must be inferred.

A delay in walking may be due to general feebleness or to paralysis of the muscles of one or both legs, and a limping gait with pain in the knee suggests hip-joint disease.

Closure of the fontanelle is retarded by the disease called rickets, and also by hydrocephalus and constitutional syphilis.

It is well to be cognizant of the fact that girls develop more rapidly than boys, and that the second or later children of the same family, by imitating their elders in the nursery, learn to talk and walk earlier than those who are born first.