How move | | | | | | | | | | | | | | | -------------------+---------+--------+---------+---------+--------- | | | | | How breathe | | | | | | | | | | | | | | | ===================+=========+========+=========+=========+========= CHAPTER VI WORMS SUGGESTIONS:--Earthworms may be found in the daytime after a heavy rain, or by digging or turning over planks, logs, etc., in damp places. They may be found on the surface at night by searching with a lantern. Live specimens may be kept in the laboratory in a box packed with damp (not wet) loam and dead leaves. They may be fed on bits of fat meat, cabbage, onion, etc., dropped on the surface. When studying live worms, they should be allowed to crawl on damp paper or wood. An earthworm placed in a glass tube with rich, damp soil, may be watched from day to day. =External Features.=--Is the body _bilateral_? Is there a _dorsal_ and _ventral_ surface? Can you show this by a test with a live worm? Do you know of an animal with dorsal and ventral surface, but not bilateral? [Illustration: FIG. 69.--An Earthworm.] Can you make out a head? A head end? A neck? Touch the head and test whether it can be made to crawl backwards. Which end is more tapering? Is the mouth at the tip of the head end or on the upper or lower surface? How is the _vent_ situated? Its shape? As the worm lies on a horizontal surface, is the body anywhere flattened? Are there any _very_ distinct divisions in the body? Do you see any _eyes_? =Experiment= to find whether the worm is sensitive (1) to _touch_, (2) to _light_, (3) to strong _odors_, (4) to irritating liquids. Does it show a sense of _taste_? The experiments should show whether it avoids or seeks a bright light, as a window; also whether any parts of the body are especially sensitive to touch, or all equally sensitive. What effect when a bright light is brought suddenly near it at night? Is _red blood_ visible through the skin? Can you notice any _pulsations_ in a vessel along the back? Do all earthworms have the same number of _divisions_ or rings? Compare the size of the rings or segments. Can it crawl faster on glass or on paper? [Illustration: FIG. 70.--MOUTH AND SETÆ.] [Illustration: FIG. 71.--EARTHWORM, mouth end above.]