1883.] Organic Physics. 259 
It is still to be seen whether any such providential measures 
will be adopted by the State of Michigan, the State that at pres- 
ent has more extensive lumber interests than any other in the 
Union. Should the subject receive serious attention at the hands 
of our legislators, there are two things that deserve special con- 
sideration—First, the fact that it is possible now, at slight expense, 
to retain under the direct control of the State, extensive areas of 
land, valuable for the purposes of forestry, that, so far as can now 
seen, are worthless for anything else ; second, the exact facts 
that we must have in order to determine what to plant on the pine 
barrens of this State will have to be ascertained by actual experimental 
planting on those barrens,and the sooner such experiments are in- 
stituted the sooner we may hope for the restoration, in part at 
least, of the forest wealth of the State. 
:0: 
ORGANIC PHYSICS. 
BY CHARLES MORRIS. 
(Continued from page 148.) 
HE difference in character between different muscles becomes 
here a matter of importance, since each muscle is thus 
adapted to its special duty. In the striated voluntary muscles 
only those fibers respond which are directly acted upon by nerve 
energy. But their response is rapid and vigorous, so as to pro- 
duce quick, energetic and localized motions. Inthe smooth mus- 
cles of the intestinal canal irritation yields a less vigorous result. 
But in them the energy is gradually communicated from fiber to 
fiber, so that a progressive muscular action arises, yielding the 
peculiar motion known as peristaltic. In the former case the 
fibers are energetic, but are insulated. In the latter they are less 
vigorous, but are in a degree uninsulated. In the muscles of the 
heart both these conditions exist. Its muscles are of the striped 
_ Variety, and are very energetic. They are also completely unin- 
sulated, The fibers are destitute, or nearly so, of sarcolemma, 
and inosculate with each other, so as to form an intricate fibrous 
network, This seems the most effective of all muscular arrange- 
R r vigoroùs action. There is not only quick, but general 
a pouse to every nerve excitation, though brought by but a 
sc fiber. A slight impulse brought to a single muscle fiber is 
“mediately disseminated throughout the heart, causing general 
