. Animal biology; Human biology. Parts II & III of First course in biology. Biology. ANIMAL BIOLOGY How many mature hydranths are seen in the hydroid shown in Fig. 40? Why are the defensive hydranths on the outside of the colony ? Which hy- dranths have no tenta- cles ? Why not ? Jellyfish. — Alterna- tion of Generations. - Medusa. — With some species of hydroids, a very curious thing hap- pens. — The hydranth tJiat is to produce tJie eggs falls off and be- comes independent of the colony. More sur- prising ^ ^ appear_. FIG. 43- - A JELLYFISH. ance changes entirely and instead of being hyd
. Animal biology; Human biology. Parts II & III of First course in biology. Biology. ANIMAL BIOLOGY How many mature hydranths are seen in the hydroid shown in Fig. 40? Why are the defensive hydranths on the outside of the colony ? Which hy- dranths have no tenta- cles ? Why not ? Jellyfish. — Alterna- tion of Generations. - Medusa. — With some species of hydroids, a very curious thing hap- pens. — The hydranth tJiat is to produce tJie eggs falls off and be- comes independent of the colony. More sur- prising ^ ^ appear_. FIG. 43- - A JELLYFISH. ance changes entirely and instead of being hydra-like, it becomes the large and complex creature called jellyfish (Fig. 43). But the egg of tJie jellyfish pro- duces a small hydra- like ani- mal 'which gives rise by budding to a hydroid) and the cycle is complete. The bud (or reproductive hydranth) of the hydroid FIG. 44. — A JELLYFISH (medusa).. 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 Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan Co.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1910
