Page:Popular Science Monthly Volume 13.djvu/333

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stance is jelly-like, and their body is traversed by tubes which radiate from the centre to the circumference.

The sunfish, and all the disk-shaped jelly-fishes especially, are remarkable for their stinging properties. When they come in contact

PSM V13 D333 Scyphistoma and strobila.jpg
Fig. 16.—Scyphistoma of Aurelia flavidula (Per. & LeS). Magnified about seven diameters. Fig. 17.—Strobila of Aurelia flavidula (Per. & LeS). Magnified about seven diameters. Fig. 18.—Strobila of Aurelia flavidula (Per. & LeS). Magnified fifteen diameters.

with the flesh of the bather, they cause a stinging sensation, similar to that produced by nettles. This is why they are called sea-nettles, and why in scientific books they are called Acalephæ.

Toward the close of summer the sunfish lays numerous eggs, and in the autumn it perishes. The eggs hatch into little oval bodies,

PSM V13 D333 Aurelia flavidula.jpg

Fig. 19.—Sunfish (Aurelia flavidula, Per. & LeS). Offspring of Figs. 16-18.

which swim freely about by means of minute hair-like appendages. After a time each one of these free-moving bodies attaches itself to a rock, shell, or sea-weed, and takes the form of a plant, and is then called scyphistoma (Fig. 16). As this goes on growing, it soon begins to divide into segments by horizontal constructions. By this process our little scyphistoma becomes a strobila (Figs. 17, 18). By continued