The Recapitulation Theory in Biology 39 



limits within which it ranges. These are represented at one 

 end by the views of Dendy and Haeckel, as indicated, and those 

 of the palaeontologist, Deperet, at the other. The latter re- 

 fers to Haeckel's hypothetical ancestors as "visions of the 

 mind" because no fossil evidence can be offered for them. 

 It is probably true that most naturalists and embryologists 

 do not wholly discount the phylogenetic significance of the 

 series of early embryonic stages among the Metazoa, and are 

 willing to admit that it may possibly represent in a very gen- 

 eralized fashion what actually happened in the early evolution 

 of organic forms. It may be well, however, to report here a 

 recent conservative statement apparently aimed directly at 

 the type of discussion illustrated in the quotation from Dendy 

 just given: 



"... .in the present state of knowledge we are able to separate 

 the various components of the animal kingdom into a certain 

 number of divergent groups or phyla; and that within the limits 

 of these phyla, although we are far from knowing even approxi- 

 mately in every case the course evolution has followed, yet we 

 are safe in concluding that all the diverse ramifications have 

 originated in the remote past from one common source, or type. 

 But when we attempt to go behind the phyla and discover their 

 origin and inter-relationships, we leave the firm ground alto- 

 gether and wander in a slippery and nebulous region of specula- 

 tion. 



It is true that certain hypotheses of a plausible character have 

 been suggested which have satisfied uncritical minds, and which 

 we often hear advanced as a part of ascertained science and 

 accepted in an otiose spirit. We are urged to believe that life 

 "originated" in certain chemical compounds which on attaining 

 a certain degree of complexity began to exhibit the fundamental 

 properties of life; and from these comparatively structureless 

 masses the nucleated cell was evolved and the unicellular animals 

 and plants, the Protozoa and Protophyta, made their appearance ; 

 that these gave rise to cell colonies, the Metaphyta on the one 

 hand, and the Metazoa on the other. The Coelenterate type 

 of organization is presented to us as the form in which the early 

 Metazoa had their being, and from this by the addition of the 

 mesoderm we arrive at the Platyhelmia, and from them by the 

 addition of a coelom and of metameric segmentation at the seg- 

 mented Annelid. And so by the addition and subtraction of 

 their characteristic qualities we may pass in imagination from 

 one fundamental type to another; but what is there of reality 

 in these speculations? They rest not on any objective evidence 



