character occur. The brain and the rest of the nervous system are
invigorated, the stomach has its powers of digestion improved, and the
liver, pancreas, and other organs perform their functions with more vigor.
By want of exercise, the constituents of the food which pass into the
blood are not oxidized, and products which produce disease are engendered.
The introduction of fresh supplies of oxygen induced by exercise oxidizes
these products, and renders them harmless. As a rule, those who exercise
most in the open air will live the longest.--LANKESTER.] (See p. 280.)

THE WONDERS OF THE MUSCLES.--The grace, ease, and rapidity with which the
muscles contract are astonishing. By practice, they acquire a facility
which we call mechanical. The voice may utter one thousand five hundred
letters in a minute, yet each requires a distinct position of the vocal
organs. We train the muscles of the fingers till they glide over the keys
of the piano, executing the most exquisite and difficult harmony. In
writing, each letter is formed by its peculiar motions, yet we make them
so unconsciously that a skillful penman will describe beautiful curves
while thinking only of the idea that the sentence is to express. The mind
of the violinist is upon the music which his right hand is executing,
while his left determines the length of the string and the character of
each note so carefully that not a false sound is heard, although the
variation of a hair's breadth would cause a discord. In the arm of a
blacksmith, the biceps muscle may grow into the solidity almost of a club;
the hand of a prize fighter will strike a blow like a sledge hammer; while
the engraver traces lines invisible to the naked eye, and the fingers of
the blind acquire a delicacy that almost supplies the place of the missing
sense.

DISEASES, ETC.--l. _St. Vitus's Dance_ is a disease of the voluntary
muscles, whereby they are in frequent, irregular, and spasmodic motion