. First lessons in zoology. Zoology. FIRST LESSONS IN ZOOLOGY the bottoms of which have been gradually lifted above the water's surface. Similarly the rock called Tripoli, found in Sicily, and the Barbados earth from the island of Bar- bados, are composed of the shells of ancient Protozoa. Hydra.—One of the most interesting of the simple animals found in fresh-water ponds is Hydra (fig. 85). Though very small com- pared with most animals we know, it is much larger than any of the Protozoa, being when expanded nearly one- fourth of an inch long. It is also not composed of a single cell but of h
. First lessons in zoology. Zoology. FIRST LESSONS IN ZOOLOGY the bottoms of which have been gradually lifted above the water's surface. Similarly the rock called Tripoli, found in Sicily, and the Barbados earth from the island of Bar- bados, are composed of the shells of ancient Protozoa. Hydra.—One of the most interesting of the simple animals found in fresh-water ponds is Hydra (fig. 85). Though very small com- pared with most animals we know, it is much larger than any of the Protozoa, being when expanded nearly one- fourth of an inch long. It is also not composed of a single cell but of hundreds of cells. It is one of the simplest of the many-celled animals, , Metazoa. Hy- dra may be found attached to bits of sticks, stones, and leaves in pools not too stagnant. There are two common kinds, one brown and one green. Specimens should be brought into the schoolroom alive, and kept Fig. 85.—Hydra: note two tentacles j^^ ^ ^Jj^^ ^f water in thc catching an insect larva; note the building young Hydra. (Natural light. To observe the si^e, one-sixth inch; from life.) \^^\y\ts of Hj'dra, examine a live specimen, attached to a bit of leaf or stick, in a watch-glass, under the low power of a compound micro- scope, or with a good magnifier. Note the cylindrical body, attached at its base, and with a series of tentacles projecting from its free end. How many tentacles are there ,' They arise in a circle about the mouth. Have some small water-fleas in the. 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 Kellogg, Vernon L. (Vernon Lyman), 1867-1937. New York, H. Holt and Company
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