178 



METAMORPHOSES OF ANIMALS. 



as it is represented in figure 148, /, attached to a piece of 

 floating wood. 



374. There is, consequently, not only a change of organi- 

 zation in the course of the metamorphoses, but also a change 

 of faculties and mode of life. The animal, at first free, 

 becomes fixed ; and its adhesion is effected by totally 

 different organs at different periods of life, first by means of 

 tentacles, which were temporary organs, and afterwards 

 by means of a fleshy stem developed especially for that 

 purpose. 



375. The Radiata also furnish us with examples of vari- 

 ous metamorphoses, especially among the star-fishes. A 

 small species living on the coast of New England (Echi- 

 naster sanguinolentus) undergoes the following phases, 

 (Fig. 149.) 



376. If the eggs are examined by the microscope, each 

 one is found to contain a small, pear-shaped body, which 

 is the embryo, (e,) surrounded by a transparent envelop. 

 On escaping from the egg, the little animal has an oblong 

 form, with a constriction at the base. This constriction 

 becoming deeper and deeper forms a pedicle, (p,) which 

 soon divides into three lobes. The disk also assumes a pen- 

 tagonal form, with five double series of vesicles. The first 

 rudiments of the rays are seen to form in the interior of the 

 pentagon. At the same time, the peduncle contracts still 

 more, being at last entirely absorbed into the cavity of the 

 body, and the animal soon acquires its final form, (m.) 



