| Weight of bodyã | Relative weights of | Percentage weights compared with total body-weights | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 21 | 61ôñ2 | 19ôñ74 | 3ôñ71 | 12ôñ59 | 11ôñ48 | 100 | 2ôñ31 | 0ôñ49 | 2ôñ66 |
| 22 | 62ôñ9 | 20ôñ29 | 3ôñ54 | 13ôñ24 | 11ôñ82 | 100 | 2ôñ14 | 0ôñ50 | 2ôñ66 |
| 23 | 64ôñ5 | 20ôñ81 | 3ôñ66 | 12ôñ42 | 10ôñ79 | 100 | 2ôñ16 | 0ôñ46 | 2ôñ37 |
| 24 | ã | ã | 3ôñ74 | 13ôñ09 | 13ôñ04 | 100 | ã | ã | ã |
| 25 | 66ôñ2 | 21ôñ36 | 3ôñ76 | 12ôñ74 | 12ôñ84 | 100 | 2ôñ16 | 0ôñ46 | 2ôñ75 |
ã From Quetelet.
From the first portion of the table, it will be seen that none of these organs by any means keep pace with the body as a whole in regard to growth in weight; in other words, there must be some other part of the fabric, doubtless the muscles and the bones, which increase more rapidly than the average increase of the body. Heart and liver both grow nearly at the same rate, and by the {90} age of twenty-five they have multiplied their weight at birth by about thirteen times, while the weight of the entire body has been multiplied by about twenty-one; but the weight of the brain has meanwhile been multiplied only about three and a quarter times. In the next place, we see the very remarkable phenomenon that the brain, growing rapidly till the child is about four years old, then grows more much slowly till about eight or nine years old, and after that time there is scarcely