they
do not attain their full maturity until about the twenty-fifth year; and
it is stated that in persons devoted to intellectual pursuits, the skull
grows even after that age. It is plainly necessary that during this period
of bone growth the nutrition of the body should be of the best, that the
bones may be built up from pure blood, and supplied with all the materials
for a large and durable framework. Else the body will be feeble and
stunted, and so through life fall short of its purpose.

If this bony foundation be then laid wrong, the defect can never be
remedied. This condition is seen in young persons who have been underfed
and overworked. But the use of alcoholic liquors produces a similar
effect, hindering bone cell-growth and preventing full development.[8]
The appetite is diminished, nutrition perverted and impaired, the stature
stunted, and both bodily and mental powers are enfeebled.

63. Effect of Tobacco upon the Bones. Another narcotic, the
destructive influence of which is wide and serious, is tobacco. Its
pernicious influence, like that of alcohol, is peculiarly hurtful to the
young, as the cell development during the years of growth is easily
disturbed by noxious agents. The bone growth is by cells, and a powerful
narcotic like tobacco retards cell-growth, and thus hinders the building
up of the bodily frame. The formation of healthy bone demands good,
nutritious blood, but if instead of this, the material furnished for the
production of blood is poor in quality or loaded with poisonous narcotics,
the body thus defrauded of its proper building material becomes undergrown
and enfeebled.

Two unfavorable facts accompany this serious drawback: one is, that owing
to the insidious nature of the smoky poison[9] (cigarettes are its worst
form) the cause may often be unsuspected, and so go on, unchecked; and the
other, that the progress of growth once interrupted, the gap can never be
fully made up. Nature does her best to repair damages and to restore
defects, but never goes backwards to remedy neglects.

Additional Experiments.

Experiment 11. Take a portion of the decalcified bone obtained from
Experiment 4, and wash it thoroughly in water: in this it is insoluble.
Place it in a solution of carbonate of soda and wash it again. Boil it
in water, and from it gelatine will be obtained.

Experiment 12. Dissolve in hydrochloric acid a small piece of the
powdered bone-ash obtained from Ex