A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . Fig. 1167.—Two Specimen.^ of Hydra, Magnified. One con-tracted, the other in a state of moderate expansion and bearingtwo buds in different stages, m. mouth: oral cone. (AfterBorradaile, 1912.) sponges, corals, hydroids, siphonophores, bryozoa, andascidians. A colony may float free in the ocean, asis the case with siphonophores. Fig. 1169, and pelagicascidians; but usually the colonies are attached tosome solid body, and they may be very large and of. RPB dtl
A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . Fig. 1167.—Two Specimen.^ of Hydra, Magnified. One con-tracted, the other in a state of moderate expansion and bearingtwo buds in different stages, m. mouth: oral cone. (AfterBorradaile, 1912.) sponges, corals, hydroids, siphonophores, bryozoa, andascidians. A colony may float free in the ocean, asis the case with siphonophores. Fig. 1169, and pelagicascidians; but usually the colonies are attached tosome solid body, and they may be very large and of. RPB dtl Fig. 1168.—Strobila Larva of Cassiopea, Showing Both Fissionand Budding. h, bud; p, proboscis. (After Bigclow, 1900.)Magnified. great beauty. From their plant-like appearance suchanimals were long known as zoophytes. The members of a colony may be all alike, as in aSalpa chain (Brooks 1893); or they may be different,showing more or less polymorphism associated withdivision of labor. The simplest division is into nutri- :j^ m f. I tive and sexual individuals, but in the more complexcolonies there are many kinds of individuals, often somodified as to be hardly recognizable, as in the Portu-gese-nian-of-war, often seen in tlio Gulf Stream. The same individual nuiyreproduce both sexuallyand by budding, as inHydra. But in numy spe-cies there is an alternationof generations. The sim-|)lest cases are like certainhydromedusa; whose eggshatch into asexual hy-droids, which in their turnproduce, by budding, me-dusie that become sexuallymature males .and 1170. But all t
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Keywords: ., bookauthorbuckalbe, bookcentury1900, bookdecade1910, bookyear1913
