Evening journal., 1906-09-26
NATURES TUNNEL AND TUBE MAKERS

national danger. Like the piddock. the
shipwOrm makes Its tunnels wholly for
protection, for II does not feed upon the
wood chips which It rasps away.
No one, not even men OF science. can
tell exactly how the pddock and the ship
worm accomplish their wonderful boring
feats. Some have thought that the work
was done by means OF constant rasning
produced by the movement OF the shell;
others that the 1eshy muscular foot OF
the animal represented the chief tool.
while still others have held that the con-
stant action OF the water pumped. as II
were. through the body OF the mollusk
against the sides Of its crypt effected the
gradual enlargement necessary as the
creature increased In size. As n matter
OF fact, It Is highly probable that com
bination OF all these means render the
shipworm and the piddock the expert tun-
nelers which we see them TO be.
One point about the shlpworm's tunnels
Is of especial interest. They are lined
with a layer of hard. shelly material 10
exactly the same way the human engi-
neers line their borings with stone or
brickwork or with n tube Of steel. This
shelly lining prevents the wood from
swelling and bulging Inward and insures
the free passage Of water along the tun-
mel. This Is very necessary. ns we nave
seen the shipworm relies upon n constaiic
supply OF sea water In order TO feed AS
its tunnels are often Of great length. It
must make sure that no stoppage shall
occur. or else run the risk OF being
starved to death.
much thicker shelly lining Is con-
structed bv n cousin OF the shipworm,
known as the cyphus. 1t makes long tun-
nels IN the sand of the sea bottom Thus.
II Il did not construct a reliable casing
with its burrow. II would very soon be
cut or by ''fall'' OF sand behind 1t and
perish. like a miner imprisoned by sud
den subsistence OF rock OF coal. In fact.
the shipworm and cyphus 'shore up the
sides OF their tunnel in exactly the man.
ner which modern engineers agree to be
the best. namely. Dy constructing tube
within the boring as the work progresses
These shelly tubes are sometimes dug out
OF the sand by the South Sea islanders
in sections varying from four to six feet
long. and are valued highly by the hnd-
ers as charms. They are placed above
the doorposts OF the huts just as we
sometimes nail up a horseshoe. Vertical
shafts are sunk by certain mollusks
termed aspergilium, and these. too, are
lined with shelly material The tops are
rooted over In very pretty way. the edge
being frillcd and the covering studded
with holes like the rose Of a watering
pot In this way undesirable intruders
are kept out. while free passage for wa
ter is preserved.
one other example Of nature tunnel
makers are the "long horn" beetles Rep
resentatiVes of these insects are found In
an parts Of the world. They are cf all
sizes. from great fellows several inches
long TO little chaps less In Size than nies.
/ Th grulls do Immense damage IN many
/ nnrfs OF the civilized globe At.the sunie
/ time II is fact that IN tropical forests
these beetles do good service H. prcSefN-
I Ing what Is called the .hnlnnc. ~ iia-
| ture." They are scavcugrrS They clear
away the vast amount OF fallen timber
which accumulates each year.