Now, there is no need of explaining the prophylactic importance of observations such as these! A child who for a period of twenty days is in a state of incubation, is called upon to struggle, with all the forces of immunity that his organism possesses, against a cause of disease which has already invaded him; yet no external sign betrays this state of physical conflict. Consequently, the child's organism continues to sustain the customary loss of energy due to the activities of its daily life, and by doing so lessens its own powers of immunity. To prescribe rest, if nothing more, for a child suspected of passing through the period of incubation would in many cases mean the saving of a life, and at the same time would protect his companions from infection, which is communicable even during the period of incubation.
In our biographic records of defective children, which include the great majority of the weakly ones, we find in many cases a characteristic tendency to relapses in all kinds of infective diseases, from which they regularly recovered. Such organisms, feeble by predisposition, yet sufficiently strong to recover from a long series of illnesses, were exhausted in respect to those biological forces on which the normal growth of the individual depends, by this sort of internal struggle between the organic tissues and the invading microbes. No scheme of special hygiene for children of this type can help us, either in the home or at school; the daily variations in weight, on the contrary, might constitute a valuable guide for the protection of such feeble organisms; at the first signs of a diminution in weight, such children ought to be subjected to absolute repose.
The use of the weighing-machine, both at home and in school cannot be too strongly recommended. In America the pedagogic custom has already been established of recording the weight of the pupils regularly once a month; but instead of once a month, the weight ought to be taken every day. The children might be taught to take their own weight by means of self-registering scales, and to compare it with that of the preceding day, thus learning to keep watch of themselves: and this would constitute both a physical exercise and an exercise in practical living.
The weight may be considered by itself, as a measurement of the body; and it may be considered in its relation to comparative mean measurements given by the authorities; just as it may also be considered, in the case of the individual, in its relation to the stature.
a. The weight, taken by itself, is not a homogeneous or rigorously scientific measurement. In the same manner as the stature, it represents a sum of parts differing from one another, the difference in this instance being that of specific gravity. As a matter of fact, it makes a great difference whether a large proportion of the weight of an individual is adipose tissue, or brain, or striped muscles. Each of the various organs has its own special specific gravity, as appears from the following table:
| Specific Gravity | ||
|---|---|---|
| Tubular bones | 1.93 | |
| Spongy bones | 1.24 | |
| Cartilage | 1.10 | |
| Muscles | from | 1.10 |
| to | 1.30 | |
| Tendons | 1.16 | |
| Epidermis | from | 1.10 |
| to | 1.19 | |
| Hair | from | 1.28 |
| to | 1.34 | |
| Liver | 1.07 | |
| Kidneys | 1.04 | |
| Brain | 1.039 | |
| Cerebrum | 1.036 | |
| Cerebellum | 1.032 | |
| Adipose tissue | 0.97 | |
All these specific gravities are low; we weigh but little more than water; and for that reason it is easy for us to swim. But because of the difference in their composition, the total weight of the body gives us no idea of its constituent parts.
Take for example the question of increase in weight. We can compare the mean figures given by the authorities with the ascertained weight of some particular child of a given age, so as to keep an empirical check upon the normality of its growth. But since we know that an individual in the course of evolution undergoes profound alterations in the volumetric proportions of the different organs in respect to one another, we cannot obtain from the total weight any light upon this extremely important alteration in proportions. Thus, for example, Quétélet gives the following figures of increase in weight for the two sexes:
| Weight | Weight | ||||
|---|---|---|---|---|---|
| Age | Males | Females | Age | Males | Females |
| 0 | 3.20 | 2.91 | 15 | 46.41 | 41.30 |
| 1 | 10.0 | 9.30 | 16 | 53.39 | 44.44 |
| 2 | 12.0 | 11.40 | 17 | 57.40 | 49.08 |
| 3 | 13.21 | 12.45 | 18 | 61.26 | 53.10 |
| 4 | 15.07 | 14.18 | 19 | 63.32 | — |
| 5 | 16.70 | 15.50 | 20 | 65.0 | 54.46 |
| 6 | 18.04 | 16.74 | — | — | — |
| 7 | 20.16 | 18.45 | 25 | 68.29 | 55.08 |
| 8 | 22.26 | 19.82 | 30 | 68.90 | 55.14 |
| 9 | 24.09 | 22.44 | 40 | 68.81 | 56.65 |
| 10 | 26.12 | 24.24 | 50 | 67.45 | 58.45 |
| 11 | 27.85 | 26.25 | 60 | 65.50 | 56.73 |
| 12 | 31.0 | 30.54 | 70 | 63.03 | 53.72 |
| 13 | 35.32 | 34.65 | 80 | 61.22 | 51.52 |
| 14 | 40.50 | 38.10 | — | — | — |
INCREASE IN WEIGHT OF BODY
According To Sutils