198 METAMORPHOSES OF MAN 



Pluieus paradoxus ; followed up his researches in the 

 Mediterranean and Adriatic; and in 1848 commenced 

 a series of publications, which added another chapter 

 to the history of the development of animals.* 



Like all his predecessors, Miiller saw that the 

 Echinoderms deposited ova from which ciliated larvae 

 were produced.f These larvae are spherical at first; 

 then they become elongated, acquire a calcareous 

 framework, formed of long and slender branches, and 

 assume the strangest forms, being sometimes like a 

 painter's easel, and at others like a double ladder with- 

 out rungs. The arms are in some instances covered with 

 vibratile cilia, but in others the latter are arranged in 

 tufts, and are of service in the locomotion of these 

 peculiar beings, which swim about with considerable 

 rapidity. All these have a complete digestive 

 apparatus, with a large and distended stomach. It 

 is upon the very walls of the latter organ, and upon 

 one of its sides, that the future echinoderm begins to 

 show itself. In the sea-urchins and the Ophiuridse 

 it appears as a circular flattened disk, which seems 

 to mould itself, as it were, upon the stomach, and 



* "Ueber die Larven raid Metamorphose cler Echinodermen." 

 Six fasciculi appeared at different intervals ; they were very care- 

 fully analyzed by M. Dareste in the " Ajmales des Sciences natu- 

 relles," for 1852 and 1853. 



f This mode of reproduction, however, is not general among 

 Echinoderms. Certain species of the Ophiuridce, animals closely 

 related to the star-fish, are ovo-viviparous. This I ascertained in 

 1842. — (Comptes Kendus Hebdomadaires de 1' Academic des 

 Sciences.) I took from the abdomen of a single mother, six per- 

 fectly formed young, which, when placed in vessels of sea-water, 

 lived as though they had been born naturally. More importance 

 is, I believe, given to this observation in the works of my confreres 

 who have met with very different phenomena in other species. 



