The Atlanta constitution. [volume] (Atlanta, Ga.) 1885-19??, 1900-03-05

category Of iointCd appendices, as these
are merely mutations OF the external Gov
ering of the insect. Referring again 10
segment. the unE of structure in the
arthropod we find that an individual seq
ment is composed of pieces more or less
movable Upon each other. In the 1hordc-
IT, segments we find this division carried
the farthest. That This is necessary is at
once seen from the fact that there must
be "A greater freedom of movement here,
to allow for the. action cf the wings IN
flight and the legs i'm walking and run
ming. The abdominal sagments do not
show divisions 10 such an extent now
ever we recognize in an individual alb
dominaI segment three subdivisions. 1hat
portion Of the segment which eNtchdS
from the sides over tho back Is known
as the dOrsum; the Ve1trdl portion i
known as the stcrnum. Where the dor
sum and the sternum meet on each side
there is more or less evident DIVISION
known AS the turgum. These divisions IN
the abdominal segments allow for all the
movements necessary for the respiration
Of the insect il will be noticed in th2
study of an insect that the external Gov
ering is more or less hard, this is made
so by the deposition of an organic com
pound in the skin known as Chltine In
Vertebratcs the skeleton or the surface
for the attachment OF IluStltS II Nit lltN
inside of the animal In insects the skei-
eton is on the outside To the inner sur
face of this outside crust of an insect the
various muscles are attached (which en-
able it to perform the various duties OF
its life.
BY q study Of figure 1. IL Will he OBJ
served that the body is divided into three
distinct resions-thc head the thoraN and
the abdomen. In the crustacea it Is rcmem-
b"red there is no distinct division between
the head anG the thoraX. This is like
wise true in the arachnida- In the milli-
peles. or thousdud-leggcd worms the
head is distinct. but there is no separd-
tiun between the thoraN and alb iomen. in
the insect body. however. We see for the
first time "a distinct division between the
head thoraX and abdomen. Let rs take
up these divisions separately taking the
head first. We may classify its parts rs
fixed and movable. The movable pa.,s
are the antennac ldbrum. manfibles.
maxllac. labium and the maxillary and
labial palpi. The most noticeable of the
fixed parts of the head are compound
eyes. the simple eyes cpicranium and the
clypeus. OF the movable parts OF the
head the antcunac are usually she most
conspicuous. These are the long-iointed
organs arising firm near the eyes ON the
rp!cranium. The uses Of the 1ntcnnae
are remarkably varied. Experiments IN
dictate Fhat in them are several different
organs Of sehse. Il is thought that the
senses of hearing, touch ana smell are
situated an these organs. The labrum is
the liplike structure which covers the
mandiblcS above Th- mandIbles are
horny appcrdages. having "a lateral mo-
ton ami are used in chewing and mac
Grating the food. The maHillac are found
beneath the maudIbicS These are rather
complicated structures. and will not be
discussed further in this connection. Each
maXilIa hears Il papt-5 or fecicr. This
organ is doubtless very sensitive 10 touch.
and il is also thought by good authorities
To he the seat Of the senses of taste and
smell. The labuu, or lower lip forms
the lower portion Of the mouth. 1t also
bears u pair of feelers or paIp
Returning TO the fixed parts of the head.
we lind that they form box mclosiug
the interior parts of the head. only one
of these parts need be considered here,
the compound yes. TINS organ has long
been a subject of much interest. 1t Is in
maay respects a remarkable structure. 1t
is composed of many single lenses grouped
together in one large eye; as many rs
% 600 may he found IN a single compound
ey e. The number OF single eyes situated
in Il compound eye varies greatly in the
fy the bee and beetle We find the eyes
quite well Developed. As 10 Just how the
insect is enabled To see with this comph-
Gated structure is still under dispute.
and as to just how definitely an insect
may see has been a matter of much eA-
pertinent. II nas been found that different
insects discern objects in widely different
degrees Of distinctness. In the dragon
fv the sense of sight Is quite we'll devel-
ored. AS a generalization II may De saiu
thar most insects are not abe To diStin-
,uish objects with much certainty except
when in motion They are readily able TO
DISTINGUISH light from darkness, and
MANY are able to distinguish the various
colors of the flowers of plants. We know
that certain species of insects are partial
to certain flowers. II may be that the
senses of smell and sight here combine TO
enable the insects to find the desired