NOTES ON THE POSTNATAL GROWTH OF THE HEART, KIDNEYS, 



LIVER, AND SPLEEN IN MAN, 



BY ROBERT BENNETT BEAN. 



Postnatal growth in man has up to the present time been inadequately treated, 

 but interest is aroused, and we may expect soon to have a much wider knowledge 

 of the subject. The normal weight of the organs is difficult to obtain, and it is 

 not easy even to determine what is normal. Averages may be misleading if 

 there are two or more types in the population. The work of Godin deserves 

 especial consideration in this connection. This author has determined the rate 

 of growth of the linear parts of the body, from birth to maturity, by multiple 

 measurements of individuals, especially those between the ages of 13 and 18 years, 

 on 100 of whom be made measurements every six months over a period of five 

 years. Some of his conclusions are as follows: 



The stature is about 50 cm. at birth; in 5 years it has attained an increase of 

 50 cm., and another 50 cm. is added between the ages of 5 and 15 years. After 

 this the stature increases to the limits of the race, sex, and environment. Indi- 

 vidual variations are important and coincident with the onset of puberty. If 

 this is early, whether in girl or boy, the 50 cm. of stature added after 5 years is 

 acquired before the age of 15; if later, after the age of 15. The stature comprises 

 the length of three segments head, trunk, and extremities. The sitting height 

 (head and trunk) doubles its birth figure at 6 years, and is three times its birth 

 figure in the adult. The lower extremities double at 4 years, triple at 7 years, 

 and quadruple at 15 years. The period elapsing between birth and puberty is 12 

 to 17 years, 2 years complete the period of puberty, and 3 years are needed after 

 this for maturity. 



Godin has compiled certain laws relating to the alternation of growth and rest 

 periods, which parallel the law of alternation in development stated independently 

 by me: 



Godin (1914): The lower extremities grow rapidly before puberty, the trunk after 

 puberty. The increase in weight is chiefly osseous before puberty, muscular after puberty. 

 The chief growth in stature about puberty occurs during the year preceding puberty; the 

 chief increase in weight about the time of puberty occurs during the period of puberty and 

 the year following. The long bones enlarge in diameter for 6 months and elongate for the 

 next 6 months. The periods of activity and of repose, which succeed each other each six 

 months, are opposite for the two serial bones of the same extremity. 



Bean (1914): There is one period or more of acceleration, alternating with periods of 

 retardation, in the development of each structural unit or organ of the body. The periods 

 of acceleration in the development of one structure may be synchronous with the periods 

 of retardation in the development of another, and if they are adjacent they may be called 

 complementary structures. Each organ has a critical period when it is developing most 

 rapidly, and when it is probably most susceptible to its environment. The teeth and the 



265 



