. Animal physiology. Physiology, Comparative; Physiology, Comparative. 546 REPRODUCTION BY Fig. 280. Hydra, attached to duck-weed. yet its usual mode of propagation is by buds. From the side of the parent, a little knot or protuberance is seen to project; this increases in size, and assumes more of the form of a young ani- mal ; tentacula sprout from around its extremity, and a mouth or opening into its interior cavity is formed there; this cavity, which at first communicates with the stomach of the parent, is gradually shut off from it; the young animal begins to seize and digest its o
. Animal physiology. Physiology, Comparative; Physiology, Comparative. 546 REPRODUCTION BY Fig. 280. Hydra, attached to duck-weed. yet its usual mode of propagation is by buds. From the side of the parent, a little knot or protuberance is seen to project; this increases in size, and assumes more of the form of a young ani- mal ; tentacula sprout from around its extremity, and a mouth or opening into its interior cavity is formed there; this cavity, which at first communicates with the stomach of the parent, is gradually shut off from it; the young animal begins to seize and digest its own food, whilst still attached by its base to the body of the parent; and at last the connexion is broken, and it becomes completely independent. Several of these buds, in dif- ferent stages of development, may sometimes be seen on the body of a well-fed Hydra (as shown on the left-hand side of Fig. 280); and occasionally the young ones themselves begin to produce a third generation, before they are separated from the body of the parent; so that as many as 18 individuals, in various stages of development, have been seen sprouting from a single one. The Sea-Anemone has a power of reproducing lost parts almost equal to that of the Hydra; but it does not propagate itself in the same manner, its reproduction being always effected by ova. But these eggs are not unfrequently hatched, and the embryos partially developed, within the body of the parent; so that the half-formed young ones are ejected from its mouth, along with the undigested remnants of its food (§. 132). 726. Among the compound Polypifera, we find the process of reproduction by budding carried to a great extent. The buds do not originate, however, from the individual polypes, but from the tree-like structure which connects them (§. 133). This structure has powers of growth in itself, independently of the polypes, which may be regarded as the mouths by which it obtains its food; and when it extends itself, by commencin
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