Page:Popular Science Monthly Volume 6.djvu/605
BIOLOGY FOR YOUNG BEGINNERS.
ster's eyesight must be very good, for, besides having all those eyes, the stalks are jointed so that he can turn them in different directions. The nerve which goes to the eye is called the optic nerve, and it is connected with each square by pretty rods and cones, which look like those in your own eye (Fig. 27). The rods and cones are covered with coloring-matter or pigment, which turns red when it is boiled. The optic nerve is a nerve of sensation, because it gives the lobster the sense of sight.
Now, where are the lobster's ears? Not in the foot, as the mussel's, but in their proper place—the head. If you look at the base of the little feelers, on each side you will find a little three-cornered slit, covered with hairs (Fig. 28). This slit leads into a small sac filled
|Fig. 28.—Little Feeler, or Antennule, showing Ear-Tube at its Base.}}||Fig. 29.—The Lobster's Ear.}}|
with water. One side of this sac is pushed inward to form a sort of fold or pocket, in which a nerve which comes from the brain or head—ganglia—spreads itself out (Fig. 29). The side of the pocket toward the water is covered with fine hairs, and these hairs touch against little bits of sand which get into the water through the outside slit (Fig. 30). These particles of sand are like the tiny stones or otoliths you found in the mussel's ear-sac, and they, likewise, help to increase the sound. The lobster's ear is made on much the same plan as your own; the sac is really a fold of the lobster's skin, which is pushed in as you might push in the crown of your soft hat. Now, I dare say you are wishing to hear about the lobster's bairns or little ones. The lobster's eggs are covered by a soft, sticky glue, which fastens them to the long hairs which cover the paddles under the abdomen (Fig. 22). The good mother-lobster doubles up her body so that the eggs are all folded inward safe from harm. Hundreds of eggs are carried in this way, and when the lobster is boiled they turn red and form what is