04 



LIEE, IN ITS LOWE?* FORMS. 



That order is briefly as follows : — The Polype, a fixed and 

 rooted animal, increases its own individual life for a while 

 by putting forth a succession of budding heads, but at a 

 certain period gives birth to a number of beings that bear 

 no resemblance to itself in form or habit, but are, to all 

 ntents and purposes, free swimming Medusae. Each of 

 these, after pursuing its giddy course for a time, produces 

 a number of eggs, which change into active animals having 

 the closest resemblance to Infusoria. Each of these latter 

 presently becomes stationary, and affixed to some foreign 

 body, along which it creeps, as a root- thread, shooting up 

 tubular and celled Polypes, as described in the early part 

 of this chapter. 



It is evident that this is a very different thing from the 

 metamorphosis which takes place in Insects and Crustacea, 

 where it is but one individual passing through a succession 

 of forms, by casting off a succession of garments that con- 

 cealed, and, as it were, masked the ultimate form. The 

 butterfly is actually contained within the caterpillar, and 

 can be demonstrated there by a skilful anatomist. In this 

 case, however, there are distinct births, producing in a 

 definite order beings of two forms, the one never producing 

 its image directly, but only with the interposition of a 

 generation widely diverse from it. Hence, to use the 

 striking though homely illustration of one of the first 

 propounders of this law, any one individual is not at all 

 like its mother or its daughter, but exactly resembles its 

 grandmother or its granddaughter. 



