354 THE RECAPITULATION THEORY 



what to do with Amphioxus : apparently the most 

 guileless of creatures, many view it with the utmost 

 suspicion, and not merely refuse to accept its mute 

 protestations of innocence, but regard and speak 

 of it as the most artful of deceivers. Few questions 

 at the present day are in greater need of authorita- 

 tive settlement. 



t^That ontogeny really is a repetition of phylogeny 

 rnusTTThink be admitted, in spite of the numerous 

 and various ways in which the ancestral history 

 jnav be distorted during actual development. 

 Before leaving the subject, it is worth while inquir- 

 ing __wjietrier any explanation can be found of 

 recapitulation. A complete answer can certainly 

 not be___giyen at present, but a partial one may 

 perhaps be obtained. Darwin himself suggested 

 tliaT the clue might be found in the consideration 

 that at whatever age a variation first appears in the 

 parent, it tends to reappear at a corresponding age 

 in the offspring^_but this must be regarded rather 

 as a statement _of the fundamental fact of embry- 

 ology than as an explanation of it. It is probably 

 safe to assume that animals would not recapitulate 

 unless they were "compelled to do so : that there 

 must be some constraining influence at work, forcing 

 them to repeat more oFless closely the ancestral 

 stages. It is impossible, for instance, to conceive 

 what advantage it can T>e to a reptilian or mam- 

 malian embryo to develojTgill clefts which are never 

 used, and which disappear~at a slightly later stage ; 

 or how it can Eeneti t a whale, that in its embryonic 

 condition it should possess teeth which never cut 



