jEH 
July, 1915 
HOUSE AND GARDEN 
tions among the simpler forms, has a pair of prominent compound 
eyes made up of a large number of lenses, and two or three 
simple eyes, or “ocelli,” placed between the compound eyes. The 
spider’s eyes are all simple and number 
six or eight. All the winged insects 
pass through a series of changes, called 
metamorphoses, after they leave the 
egg, in the last stage having their wings 
fully developed. Spiders pass through 
their developmental stages before they 
leave the egg, and after hatching merely 
increase in size without change of form. 
Insects have only three pairs of true 
legs; spiders have four pairs. 
We have spoken of insects and their 
allies having the body built up of seg¬ 
ments or rings. It must not be sup¬ 
posed, however, that these rings are 
separate and distinct. Taking a long 
cylindrical body, like that of a cater¬ 
pillar or a dragon-fly, for example, arid 
making a longitudinal section of it, we 
should find that it forms one continuous 
tube of skin, which has been fortified 
bv the deposit of chitin in rings, having connecting- 
rings of thin, purple skin, which allow of contrac¬ 
tion or distension in length and of lateral curvature 
of the body, as a whole or in parts. By the at¬ 
tachment of muscles from the hard to the soft 
rings such movements are brought under the con¬ 
trol of the insect. This plan of structure allows 
a considerable amount of elasticity to the body 
as a whole. 
The theoretical insect consists of twenty of these 
strengthened rings, but the whole 
twenty are not evident in most cases. 
Some of them are combined to form the 
three distinct regions of the body — the 
head, the fore-body and the hind-body 
—and one or more of the hindmost 
segments are “telescoped" so that they 
do not appear except on dissection. It 
is considered that the first four rings 
have been consolidated to form the 
head, which bears four pairs of external organs, a pair of jointed 
feelers, or antennae, a pair of compound eyes, and the appendages 
of the mouth. In like manner the next three segments have 
been united to form the fore-body or 
thorax, bearing on the lower side the 
three pairs of legs, while on the upper 
side the second and third rings bear the 
two pairs of wings. The hind-body, 
though theoretically it may have thir¬ 
teen rings, usually consists of ten 01- 
eleven, and often of a smaller number. 
The hind-body bears no appendages, 
except those connected with the func¬ 
tion of reproduction. Stings, where 
present, are modifications of these 
organs. 
The limbs of mature insects are all 
made up of several joints, and it is re¬ 
markable that these joints are con¬ 
structed on the same principle as in 
backboned creatures, and are extended 
or folded by the contraction of similar 
sets of muscles, though in the one case 
the .muscles are attached to the central 
bony portion, and in the other to the chitinous ex¬ 
terior. The number of joints in these limbs is not 
the same in all orders or families of insects. There 
is considerable variation in the terminal section of 
the legs — the foot—which normally consists of 
five segments, but may be reduced to three or two. 
In caterpillars the only true legs are the three 
pairs at the front end of the body: those in the 
middle and at the hind extremity are unjoined 
temporary structures. The jaws and sucking 
apparatus of the mouth are seen by the 
process of development within the egg 
to be essentially modified limbs. So also 
are the feelers or antennae. 
The internal organs of an insect may 
be said briefly to consist of the circula¬ 
tory system, the organs of nutrition, the 
nervous system, the breathing appara¬ 
tus, and the reproductive organs. The 
( Continued, on page 52) 
Have you ever noticed how tenaciously a caterpillar clings? 
With these terminal hooks he fastens onto the object. 1 he 
true legs just behind the head manipulate its food 
1 he tongue of a butterfly — in fact, a long trunk The leaf-cutting bee and a sample of its work, which can 
kept coiled like a watch-spring when not in use, be seen on rose bushes at this season. The pieces are 
but extended for sucking the sweets of flowers used in building the nursery 
Scales from a butterfly's wing: some are colored, 
but the color effects are often optical, due to 
the reflection of light by ridges on each scale 
