. Beginners zoology. Zoology. I u. 30 — Nettling Cli l II. discharged, and I. not discharged. nately elongating and rounding the foot. Can you dis- cover other ways by which it moves ? Docs the hydra always stand upon its foot ? Lasso Cells.—Upon the tentacles (Fig, 35) are numer- ous cells provided each with a thread-like process (Fig. 36) which lies coiled within the cell, but which may be thrown out upon a water flea, or other minute animal that comes in reach. The touch of the lasso paralyzes the prey (Fig. 37). These cells are variously called lasso cells, nettling cells, or thread cells.
. Beginners zoology. Zoology. I u. 30 — Nettling Cli l II. discharged, and I. not discharged. nately elongating and rounding the foot. Can you dis- cover other ways by which it moves ? Docs the hydra always stand upon its foot ? Lasso Cells.—Upon the tentacles (Fig, 35) are numer- ous cells provided each with a thread-like process (Fig. 36) which lies coiled within the cell, but which may be thrown out upon a water flea, or other minute animal that comes in reach. The touch of the lasso paralyzes the prey (Fig. 37). These cells are variously called lasso cells, nettling cells, or thread cells. The thread is hollow and is pushed out by the pressure of liquid within. When the pressure is withdrawn the thread goes back as the finger of a glove may be turned back into the glove by turning the finger outside in. When a minute animal, or other particle of food comes in contact with a tentacle, how does the tentacle get the food to the mouth ? By bending and bringing the end to the mouth, or by shortening and changing its form, or in both ways ? (Fig, 34, C.) Do the neighbouring tentacles seem to bend over to assist a tentacle in securing (Fig. 34, C.) Digestion.—The food parti- _ _ I'u;. 37.— 11VHKA (.apturing a cles break up before remaining water Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coleman, Walter M. Toronto : Macmillan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
