THE TOIJNG SCIENTIST. 
105 
will be found to have but six true legs. The 
spider has eight legs, but it is not an insect. 
This may surprise some of our readers who 
are not familiar with entomology, but it 
tends to show that there is a great deal to 
be learned of the most familiar animals we 
meet every day. 
Another curious fact about insects is that 
they do not breathe through the mouth, 
nor even through the head. The breathing- 
holes are called spiracles, and are placed at 
the sides of the abdomen, usually nine on 
each side. 
Insects that live under water come to the 
surface for fresh air, with the exception of 
a few that can live on the air contained in 
the water. 
Some insects possess an incredible num- 
ber of eyes. If we examine the eye of a I 
fly under a microscope, we will perceive 
what looks to the naked eye to be but a sin- 
gle eye, to contain hundreds of eyes, of a 
hexagonal shape, arranged like the cells of 
honey comb. Each of these is a separate 
eye, and instead of moving its eye from 
side to side, as we do, the insect sees with 
the eyes that are nearest the object. Some 
•of the beetles have 25,000 eyes, the dragon 
ily 12,000, the house fly 4,000, and the ant 
manages to see with 50. 
The antennae are two horn-like appen- 
dages joined to the head, one on each side, 
usually in front. Various forms are seen, 
some smooth and tapering to a point, and 
some in the form of a club, largest at the 
small end, while others are broad and 
branched like a feather. ! 
The antennse have puzzled entomologists 
more than any other organ of the insect. 
They are evidently used as feelers, and 
some have advanced the opinion that 
they are the organs of hearing as well. As 
yet no organs of hearing have been dis- 
covered. 
To he continued. 
— Among the mechanical toys at the 
Paris Exposition, are dolls that swim, dive, 
and tread water, after the most approved 
human style. 
An Interesting Experiment. 
rriHE following experiment requires no 
special apparatus, and is not only very 
striking and beautiful, but very instructive. 
It has been clearly proved that plants 
breathe, and that by that breath they live. 
Every green leaf is a delicate lung, and acts 
the same part in the economy of nature 
that the lungs of animals do; separating 
from the air that element which the growth 
of the plant demands, and discarding or 
exhaling that which is of no service. And 
just as oxygen is required by the animal 
system, so for the support of all vegetable 
life, carbon is needed. When men breathe, 
they take into their lungs oxygen, which 
there combines with the carbon of the 
blood, forming a third compound gas, 
known as carbonic acid, which is breathed 
out, and in this state is of no value, but 
rather dangerous to animal life. Were there 
no way of restoring to the air the oxygen 
which is united to carbon in this gas, then 
would all animals sicken and die. 
But, though the lungs of man and beast 
are not able to obtain the needed susten- 
ance from the dangerous gas, it is not so 
with the leafy lungs of the plant. These 
organs are so formed that they take up 
freely the carbonic acid; and as, in this 
case, the food they want is carbon, they 
retain this, and breathe back or exhale oxy- 
gen, which is now free, and ready for man's 
use again. But how can you prove this 
fact, that plants breathe out oxygen? The 
answer is given in the illustration before 
us; and, as the apparatus used is extremely 
simple, an explanation of it will best convey 
our meaning. Having placed in a glass 
funnel a few fresh green leaves, invert it in 
a tumbler of fresh water, as here shown. 
Now close the opening abo v^e, and draw ofl' 
some of the water in the glass. If this 
vessel be now placed in the sunlight, bub- 
bles of gas will form on the leaves, and rise 
into the top of the closed funnel. When a 
sufficient quantity of the gas has so col- 
lected, pour in enough water to nearly fill 
I the tumbler, remove the cork, and hold 
