View source for Paper - Notes on the postnatal growth of the heart kidneys liver and spleen in man (1919)

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| [[File:Mark_Hill.jpg|90px|left]] This 1919 historic paper by Bean describes postnatal growth of organs in humans. Published in the series [[Book_-_Contributions_to_Embryology|Contributions to Embryology]] (Carnegie Institution of Washington).
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=Notes on the Postnatal Growth of the Heart, Kidneys, Liver, and Spleen in Man=

By Robert Bennett Bean, 

Professor of Anatomy in the University of Virginia. 


With eight text-figures. 

==Introduction==

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. Tliis 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. Individual 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 liiter, 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 pubertj' occurs during the year preceding puberty; the chief increase in weight about the time of puberty occurs during the period of pubertj 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 long liones alternate in growth. The growth of the individual teeth alternates from mandible to maxilla or the reverse, and from one tooth to another at some distance from it. The head and thorax alternate in growth, the trunk and extremities, the heart and luncs, the liver and intestines.


The law of alternation in development should he of interest in its relation to the growth of the organs, and it is important to know the relation of the individual to i)uberty in any study of growth. There is also another law of development that may be illustrated by the growth of the two types in man — the hyperphylomorph and the meso-phylomorph. Two types long have been known to physicians as the phthisic and plethoric, or carnivorous and herbivorous; they have also been called the long skeleton and broad skeleton, or narrow back and broad back, but it remains to be determined whether these types are the same respectively as the hyper-phylomorph and meso-phylomorph.


If growth depends upon placental ahmentation, as stated by Godin, and if the hyi)er-i)hylomorph is precocious and the meso-phylomorph retarded in development, as determined by me (1914), and if the activities of the endocrinous glands influence growth, further studies may reveal some association of these facts, and thus enable us to link up our disconnected studies.


jNIanom-rier (1902) called attention to the macroskeles (long skeleton) and the brachyskeles (broad skeleton) in different individuals, and Godin (19 Oa\ has demonstrated that these two types differ from each other in their measurable components more than small individuals differ from tall ones, or men from women. Every transverse diameter is greater in the broad than in the long skeleton. The extremities of the broad skeleton, especially the lower, are relatively short, and of the long skeleton relatively long; but the trunk of the broad skeleton is relatively long, and that of the long skeleton relatively short. The difference in length of the trunk in the two types increases considerably- between the ages of 13 and 23 years, and becomes the most striking difference in the Uncar measurements of the vertical. These differences correspond with those between the hyper-phylomorph and meso-phylomorph. The two types should be discriminated in any study of growth.


The great growth of the extremities and of the teeth (osseous system) before puberty, and the great growth of the trunk after puberty the latter coincident with the growth of the muscles including the heart, in conjunction with the activity of the sex glands and the maturity of the systems of alimentation, circulation and respiration, undoubtedly are of importance in relation to the growth of the organs.

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