(allolobophora foetida) be cut in two in the middle, the pos- 

 terior piece regenerates at its anterior cut end, not a head 

 but a tail. "Not by the widest stretch of the imagination 

 can such a result be accounted for on the selection theory." 

 Quite the reverse case presents itself in certain planarians. 

 If the head of planaria lugitbris is cut off just behind 

 the eyes, there develops at the cut surface of the head- 

 piece another head turned in the opposite direction. 

 "These and other reasons," concludes Professor Morgan 

 (P- 381), "indicate with certainty that regeneration cannot 

 be explained by the theory of natural selection." 



The ingenuity of the Darwinian imagination, however, 

 will hardly fail to assign some reason why two heads are 

 more useful than one in the above instance, and thus recon- 

 cile the phenomenon with Darwinism. For, according to 

 Professor Morgan "to imagine that a particular organ is 

 useful to its possessor and to account for its origin be- 

 cause of the imagined benefit conferred, is the general pro- 

 cedure of the followers of the Darwinian school." "Per- 

 sonal conviction, mere possibility," writes Quatrefages, 

 "are offered as proofs, or at least as arguments in favor 

 of the theory." "The realms of fancy are boundless," is 

 Blanchard's significant comment on Darwin's explanation 

 of the blindness of the mole. "On this class of specula- 

 tion," says Bateson in his "Materials for the Study of Va- 

 riation," referring to Darwinian speculation as to the bene- 

 ficial or detrimental nature of variations, "on this class of 

 speculation the only limitations are those of the ingenuity 

 of the author." The general form of Darwin's argument, 



17 



