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SCIENCE. 



[Vol. XI. No. 259 



undivided support from the scientific world, no less than from 

 owners and masters of vessels, marine insurance companies, and, 

 indeed, from the general public, for who is not interested in lessen- 

 ing the hazards of the sea? The relations which have grown up 

 and the interchange of data now carried on between this office and 

 other scientific bureaus of the government, no less than the recog- 

 nized value of this most appropriate work for naval officers in times 

 of peace, mark a new era in naval administration, the permanency 

 of which should be guaranteed. The people of the United States 

 are quick to recognize good work, and nothing can strengthen con- 

 fidence in and support of the navy more than the assured perma- 

 nency of the praiseworthy work of the Hydrographic Office. 



THE GROWTH OF CHILDREN. 



The systematic measurement of the several parts of the human 

 body, together with the testing of their functions, has developed 

 into the science of anthropometry. The plan of establishing an 

 anthropometrical laboratory, where, for a small fee, any one can 

 have himself weighed, measured, and his powers tested, which Mr. 

 Galton has so often and so ably advocated, seems about to be 

 realized. The results of such measurements, when widely taken 

 and ably compared, will be to practical biology and hygiene what 

 statistics, in the present use of the term, are to economical science, 

 — the experimental basis of their practical application. As in the 

 latter, so in the former, the stating of these results in accurate form 

 at once opens up a number of questions never before considered, 

 and at the same time helps to solve those that have been brought 

 to notice. In this department of study no field has been cultivated 

 with so much zeal as the study of the growth of children, mainly 

 because this is a field where the practical lessons can be most 

 effective. In a recent number of a German scientific journal. Pro- 

 fessor Gad of the University of Berlin, sums up the recent studies 

 upon the growth of children, and thus makes accessible some very 

 interesting facts. 



About one-fourth of a human life is spent in the period of 

 growth ; and this implies not merely addition of material, but as- 

 similation, re-formation. It involves, too, in some cases, the en- 

 largement and change of form of elementary cells, but in most 

 cases the formation of new cells by cell-division. We know more 

 about the growth of the skeleton than about that of the soft parts 

 of the body ; but a more detailed knowledge of the growth of its 

 several parts is highly desirable. The height and weight of the 

 entire body are the most readily observed, and about them the in- 

 formation is most accurate. The female child weighs, on the aver- 

 age, 3, and the male 3.5 kilograms. At the fifteenth year the 

 weight has become twelve times this amount. The greatest 

 changes occur in the first year. At the end of the second year, the 

 body weighs three and a half times its original weight, and about 

 one-fifth more than at the end of the first year. In the third year 

 it increases by one-tenth its weight ; and from then on, the increase 

 is tolerably constant up to the eighth year for girls, and the tenth 

 year for boys, at about 1,500-1,800 grams per annum. The in- 

 crease in height takes a parallel course. The greatest changes 

 occur in the suckling. At birth the height is 50 centimetres, which 

 is about one-third that of the adult. At twelve months it has in- 

 creased by 20 centimetres (40 per cent), more of this increase go- 

 ing to the lower than to the upper half of the body. In the second 

 year the increase is 10 centimetres (15 per cent); in the third, 7 

 centimetres (8 per cent) ; and from then on, it is about 5 centi- 

 metres annually. At five years the height has doubled, and at fif- 

 teen tripled itself. This for boys. Girls are smaller, and reach 

 their maximum earlier. The maximum height of army recruits 

 falls between the twentieth and the twenty-second year, and is 

 170.5 centimetres. If in growing the body retained the proportions 

 of the several parts, the weight of the adult would be twenty-seven 

 times that of the new-born child, inasmuch as the adult is three 

 times as tall as the babe, and the volume is as the cube of the 

 height. As it is, the adult weight is only twelve times the original, 

 and this difference shows how much more the growth is in height 

 than in any other direction. 



The usual method of obtaining these average results is to meas- 

 ure groups of children of certain ages, and take the mean result. 



Another method is to observe the same children, and measure and 

 weigh them for many years. The latter is the more troublesome, 

 but the inference from it is more immediate ; though the former, 

 when based on sufficiently large numbers, gives reliable results. 

 Dr. Landsberger has been measuring a large number of children in 

 Posen, Germany, and always the same children, since 1880, — a 

 period of six years. The measurements have been made always 

 between the 5th and the 15th of May, at the same time of day, in 

 the same place, and with the same instruments. The average 

 period covered is from the sixth to the thirteenth year. One curious 

 result is, that the social factor as between the rich and the poor is a 

 much more important one than the racial as between Poles and 

 Germans. The rich children come to school taller and heavier 

 than the poor ones, though their increase after getting to school is 

 not more rapid. This long-lasting effect of early care is much more 

 conclusively shown by the figures of another observer, Russow, whO' 

 has tabulated the heights and weights of children from their second 

 to their eighth year, distinguishing between those that were natu- 

 rally suckled and those that were artificially reared, and throughout 

 all this period shows a balance in height and weight in favor of the 

 former. 



Perhaps the most original investigation in this field is that of Dr. 

 Malling-Hansen, director of the institute for the deaf-and-dumb at 

 Copenhagen ; the measurements being made on the children of 

 that institution ranging from nine to fifteen years in age. The 

 weights of these children show three marked periods in each year : 

 there is a period of maximum growth in weight extending from 

 August to the middle of December, a period of mean growth in 

 weight from then to the first of April, followed by a period of min- 

 imum growth in weight back to August again. During the period 

 of maximum growth in weight, the daily increase is three times as 

 great as during the period of mean growth ; and almost all that is 

 gained in the latter period is lost in the period of minimum growth. 

 With regard to height, these periods are equally evident though not 

 coincident. In Copenhagen the period of minimum growth in 

 height is from August to the end of November ; the mean period,, 

 from then to March; and the maximum period, from March to 

 August. In the maximum period the daily increase in height is two 

 and a half times as great as in the mean period, and in the latter 

 two and a half times as great as in the minimum period. 



The period, then, at which the general increase of the body is 

 going on is from the end of March to December ; and within this 

 period there is a period of maximum increase in height and a 

 period of maximum increase in weight. During the period of most 

 rapid increase in weight, the increase in height is the slowest of any 

 in that period, the times of mean growth of height and weight about 

 coincide, and the period of maximum growth in height is a period of 

 comparative rest for the weight. The height-periods begin and end 

 about fifteen days before the weight-periods. The height first has 

 a period of minimum growth, then a period of mean growth, then 

 its maximum growth, and then suddenly falls back again to the 

 minimum rate of growth. The weight, however, begins with a 

 minimum rate of growth, passes at once to its maximum, and then 

 slowly falls through the period of mean growth back to the mini- 

 mum again. The growth in weight varies more than the growth 

 in height. An increase of i centimetre of height corresponds to 

 2.84 kilograms during the period of maximum growth in weight, 

 but only to .48 of a kilogram in the period of mean or minimum 

 growth. The increase of weight in the maximum period is essen- 

 tially a growth in stoutness, and the loss of weight during the 

 period of minimum growth is a decrease in stoutness. In the 

 period of maximum increase in height the increase in stoutness is 

 at a minimum, and during the period of least increase in height is 

 at a maximum. A practical lesson to be derived from the knowl- 

 edge of these periods is to have as large as possible a share of the 

 period of general greatest growth fall into the vacation- time ; for 

 then the body has less strain upon it, and is in general in the best 

 condition for growing. The Swedes and South Germans are ac- 

 cordingly right in giving their children two or two and a half 

 months vacation, from July to the middle of September, thus in- 

 cluding a good share of the greatest growth period. 



Dr. Malling-Hansen has also attempted to make out shorter 

 periods of twenty-five and seventy-five days of variations in growth. 



