1883.] Organic Physics. 261 
place, while the products of previous oxidation are carried away, 
and new oxygen stored up within the cells. 
Such is the systole and diastole of the whole system. Life has 
its instigating and governing agency in the contact of foreign 
matter with nerve extremities, the consequent oxidation of muscle 
tissue, and the resulting motor activity. It rests and repairs when 
contact ceases, or the exhausted nerves grow irresponsive. With- 
out contact there could be no life. The body of man is a delicate 
instrument, played upon by the fingers of the universe, and re- 
sponding in harmonious motions to the finest touch. But it must 
have its intervals of rest, in which its relaxed strings can be keyed 
up again to the concert pitch of active vitality. Could a sleeping 
body be so situated that no influence, either physical or mental, 
could act upon it, it could never waken. But it cannot be so 
situated. In the deepest slumber fine touches of exterior matter 
constantly seek the nerve extremities. In time the repaired 
frame grows again responsive. Nowa touch calls a muscle into 
action. Now an impression makes its way through the brain to 
the mind. The heart, which had lost vitality through an excess 
of oxidation, during the day, has regained it by an excess of 
nutrition during the night. The blood current pours rapidly 
through the body, the animal energies break into full play, and 
the daily flow of the tide of life succeeds its nightly ebb. 
Protoplasm, whenever so situated as to expose it to external 
contact, displays the general results above considered. The pro- 
toplasm of plants is as sensitive as that of animals, but ordinarily 
IS Covered with a more impervious coating, which hinders the 
communication of vibrations from cell to cell. It is also, prob- 
ably, less freely permeated by oxygen. Yet leaves have general 
motions which are instigated, in most cases at least, by external 
contact. Many leaves move in response to the vibrations of 
light, and many othersin response to touch. Possibly the seemingly 
anite motions of climbing plants may be thus instigated. In 
the meat-eating plants the contact influence is often conveyed to 
Considerable distances, but these movements are usually deliberate, 
as if the partial insulation of the cells hindered their progress. The 
Motor energy is propagated most rapidly in the line of the long 
_ meter of the cells, in which direction there are fewer interrup- 
re to its 
Movement. Many plant motions are known to be 
to a peculiar action of elastic cell membranes, and a forcing 
