FUNDAMENTAL RELATIONS OF ANIMALS 85 



pole exemplify the structure and form of those Ichthyoids which 

 have either no legs or very imperfect legs, with and without external 

 gills; next it assumes a shape reminding us more of the Tritons and 

 Salamanders and ends with the structure of the Frog or Toad. A 

 comparison between the two latter families might prove further that 

 the Toads are higher than the Frogs, not only on accoimt of their 

 more terrestrial habits (see Sect, xvi), but because the embryonic 

 web, which to some extent still unites the fingers in the Frogs, disap- 

 pears entirely in the Toads, and may be also because glands are 

 developed in their skin which do not exist in Frogs. A similar com- 

 parison of the successive changes of a new species of Comatula 

 discovered by Prof. Holmes, ^''^ in the harbor of Charleston, in South 

 Carolina, has shown me in what relation the different types of Cri- 

 noids of past ages stand to these changes, and has furnished a stand- 

 ard to determine their relative rank; as it cannot be doubted that 

 the earlier stages of growth of an animal exhibit a condition of rela- 

 tive inferiority, when contrasted with what it grows to be after it 

 has completed its development and before it enters upon those phases 

 of its existence Avhich constitute old age and certain curious retro- 

 grade metamorphoses observed among parasites. ^^*^ 



In the young Comatula there exists a stem by which the little ani- 

 mal is attached, either to sea weeds or to the cirrhi of the parent; the 

 stem is at first simple and without cirrhi, supporting a globular head 

 upon which the so-called arms are next developed and gradually com- 

 pleted by the appearance of branches; a few cirrhi are at the same 

 time developed upon the stem, which increase in number until they 

 form a wreath between the arms and the stem. At last, the crown 

 having assumed all the characters of a diminutive Comatula, drops 

 off, freeing itself from the stem, and the Comatula moves freely as 

 an independent animal. 



I™ [Francis S. Holmes, 1815-1892.] 



"" [Agassiz returns to this concept repeatedly, because it represents his particular 

 understanding of "evolution" and "development." He consistently identifies change in 

 the individual (ontogeny) with change in the type or race (phylogeny). Ontogeny was 

 therefore a recapitulation of phylogeny, illustrating the so-called "biogenetic law." 

 Change, therefore, was primarily individual variation that took place according to a 

 preordained plan and pattern. This concept fitted in quite nicely with Agassiz's crea- 

 tionism. Contrary to some late nineteenth-century advocates of the evolution concept 

 like Ernst Haeckel (1834-1919), it is not at all necessary for the validation of the 

 idea of evolution.] 



