248 THE PREDOMINANCE 



CHAPTER XV. 



THE MIMETIC FORMS OF DIVERSE TYPES OF ANIMALS. 



MY principal aim in the last lecture was to show, by compar- 

 ison, the distinct lines of separation which exist between the Jive 

 grand divisions, which I had stated were characterized, in the 

 several groups, by certain relations, through means of which they 

 might be recognized, and distinguished, the one from the other. 

 Thus the Protozoa are characterized by the relation of their or- 

 ganization to a spiral (p. 175). The Zob'phyta repeat their 

 organization in para/lei lines, along- the length of the body (p. 

 177). The Mollusca are based upon a uniformity of organiza- 

 tion ; they are monomerous (p. 105). The Articulata repeat their 

 parts from point to point along the body, so that it appears jointed 

 from one end to the other (p. 214). And the Vertebrata have 

 an upper and a lower region, separated from each other by the 

 vertebral axis (pp. 126, 231). I then referred to the so-called 

 transitions from one division to another, and showed that they 

 could not hold out, that they were illusory. 



Now the reason why it has been, and is, even at the present 

 day, so difficult, in some instances, to discover the proper posi- 

 tion of certain animals, is twofold. In the first place, it often 

 happens that a newly discovered creature is not in its adult state, 

 and in consequence of a lack of development its characteristics 

 have not been marked out. 



You will recollect that I have said that all animals in their 

 earliest stages of growth possess certain characters in common. 

 This is the condition in which animals, belonging to one grand 

 division, may oftentimes be mistaken for those of another 

 division. How much, for instance, this figure (fig. 145) of a 

 young Starfish, or this of a young Molluscan (fig. 149), resembles 



