Examine a live specimen placed on moist paper or wood. Note the characteristics of its locomotion, and the movements of its body-parts. How do the setæ aid in locomotion? =Internal structure= (figs. 25, 26 and 28).--TECHNICAL NOTE.--With a fine-pointed pair of scissors make a dorsal median incision, not too deep, behind the clitellum and cut forward as far as the first segment. Put the specimen into dissecting-dish, carefully pin back the edges of the cut and cover with clear water or, better, 50% alcohol. Note the long body-cavity divided by the thin _septa_ which have been torn away for the most part by the pinning process. Note the thin transparent covering of the body, the _cuticle_. Just beneath this note a less transparent layer, the _epidermis_, and underneath this a layer of muscles. The _muscular layer_ is made up of two clearly recognizable sets, an outer circular layer and an inner longitudinal layer the fibres of which are continuous with the septa. Note, as the most conspicuous internal organ, the long _alimentary canal_, of which a number of distinct parts may be recognized. Most anteriorly is a muscular _pharynx_, which is followed by a narrow _œsophagus_, leading directly into the thin-walled _crop_; next comes the muscular _gizzard_, and next the _intestine_ which opens externally in the terminal segment through the _anus_. The anterior end of the alimentary canal is more or less protrusible, while the posterior portion is held more firmly in place by the septa which act as mesenteries. Surrounding the narrow œsophagus are the reproductive organs, three pairs of large white bodies and two pairs of smaller sacs. Note the _dorsal blood-vessel_ lying along the dorsal surface of the alimentary canal, from the anterior portion of which arise several _circumœsophageal rings_ or "hearts." These hearts are contractile and serve to keep the blood in motion through the blood-vessels (see later). In the most anterior of the body segments note the pear-shaped _brain_ or _cerebral ganglion_. TECHNICAL NOTE.--Lift carefully to right and left the reproductive organs, thus exposing the œsophagus. Note three pairs of bag-like structures projecting from the œsophagus. The front pair is the _œsophageal pouches_; the next two pairs are the _œsophageal_ or _calciferous glands_. They communicate with the alimentary canal, and their secretion is a milky calcareous fluid. Make a drawing that will show all the parts so far studied. TECHNICAL NOTE.--Cut transversely through the alimentary canal in the region of the clitellum and carefully dissect the anterior portion of the canal away from the surrounding organs.