Is the body segmented? Is the body composed of _head_, _thorax_ and _abdomen_? Note the soft, flexible, weakly-chitinized condition of the _body-wall_. How many pairs of legs are there? Where are they situated? Is there any difference in the various legs? If so, what is the difference? Which of the legs of the larva correspond with the legs of the butterfly? Why? The prothoracic segment and the abdominal segments 1 to 8 each bear a pair of _spiracles_ (small blackish spots on the sides). Are both _compound_ and _simple eyes_ present? How many eyes are there? Are there _antennæ_? Dissect out the _mouth-parts_. How do they differ from those of the butterfly? Are they more like the mouth-parts of the butterfly or more like those of the locust? With fine sharp-pointed scissors make a shallow longitudinal incision along the whole length of the dorsal wall. In a freshly-killed specimen a drop of pale greenish blood will issue as the scissors' point is first thrust through the skin. Put a droplet of this blood on a glass slide, cover with cover glass and examine with high power of the microscope. Note that the blood is a fluid containing numerous sub-circular or elliptical bodies, the _blood-corpuscles_. Note at least two kinds of corpuscles: most abundant a granular, circular kind, the true blood-corpuscles; and rarer, a larger, clear, usually elliptical or oval, but sometimes irregular and amœbiform kind, generally spoken of as _fat-cells_. Make a drawing of the corpuscles in the field of the microscope. After making the dorsal longitudinal incision pin out the caterpillar in the dissecting-dish with dorsal aspect uppermost. When the edges of the skin are pinned back, the organs most conspicuous in the body-cavity will be the flocculent masses of _adipose tissue_, the large, simple, tubular _alimentary canal_ usually dark or greenish because of the color of its contents, and the numerous silvery _tracheal tubes_. In those caterpillars which spin a silken cocoon, the _silk_ or _spinning-glands_ are usually long and prominent. They lie on either side of the anterior part of the alimentary canal, and open by a common duct on the labium. Rising from behind the middle of the alimentary canal may be found the long, whitish, folded and twisted _Malpighian tubules_. By picking away the fat masses, expose the full length of the alimentary canal. Note its great size (large diameter). Is it divided into distinct regions such as crop, proventriculus, stomach, intestine, etc.? How is it held in place? Trace the principal longitudinal tracheal trunks. Find, if you can, a pair of small compact bodies usually somewhat elongate, one lying on each side of the posterior part of the alimentary canal. These are the rudimentary reproductive organs.