16 ANTHOZOA HYDROIDA. 



life, while by the latter the species is multiplied and con- 

 tinued. 



The bud is a shoot merely from the pulpous axis of the 

 polypidom, or from the body of the naked species, and is 

 identical in structure with the part of the parent whence it 

 pullulates. Every species begins its existence with a single 

 polype, which, by the evolution of a succession of buds, after 

 an order peculiar to each, grows up to a polypidom that may 

 contain many hundreds of tenants. On the regulated jn'oduc- 

 tion of these buds the upward growth and character of the 

 polypidom depends ; and simultaneous with its growth, the 

 fibres by which it is rooted extend and increase them- 

 selves, and, at uncertain intervals, give existence to similar 

 buds, whence new polypiferous shoots take their origin, 

 for these root-fibres are full of the same living medullary 

 substance with the rest of the body. To use the words of 

 Ellis, — " These tubes not only secure it from the motion 

 of the waves, but likewise from these rise other young 

 animals or corallines, which growing up like the former, with 

 their proper heads or organs to procure food, send out other 

 adhering tubes from below, with a further increase of these 

 many-headed branched animals ; so that in a short time a 

 whole grove of vesicular corallines is formed, as we find them 

 on oysters, and other shell-fish, when we drag for them in 

 deep water."'" 



" New buds and bulbs the living fibre shoots 

 On lengthening branches, and protruding roots ; 

 Or on the father's side from bursting glands 

 The adhering young its nascent form expands ; 

 In branching lines the parent trunk adorns. 

 And parts ere long like plumage, hairs, or horns. "t 



In the fresh-water Hydrse the bud bourgeons apparently 

 from any point of the body, evolves, gradually assumes the 

 port and aspect of the parent, and then, by a natural process 

 of atrophy, detaches itself and goes away to act its part inde- 

 pendently amongst the entities of nature. 



The eggs or ovules by which the species is continued are 

 of several kinds. The first we shall notice have been called 



* Ellis and Solander's Zoophytes, p. 33. 

 t Darwin, Temple of Nature, canto ii. 



