48 THE CASE AGAINST EVOLUTION 



cestry in the case of homologous forms is based, not upon this 

 or that particular likeness, but upon an entire group of coor- 

 dinated resemblances; (2) that the resemblances involved are 

 not exterior similarities, but deep-seated structural uniformi- 

 ties perfectly compatible with diversities of a superficial and 

 functional character. "Nothing," says Dr. W. W. Keen, "could 

 be more unlike externally than the flipper of a whale and the 

 arm of a man. Yet you find in the flipper the shoulderblade, 

 humerus, radius, ulna, and a hand with the bones of four 

 fingers masked in a mitten of skin." (Science, June 9, 1922, 

 p. 605.) 



In fact, the resemblances may, in certain instances, be so 

 deeply submerged that they no longer appear in the adult 

 organism at all and are only in evidence during a transitory 

 phase of the embryological process. In such cases, the embryo 

 or larva exhibits, at a particular stage, traces of a uniformity 

 completely obliterated from the adult form. In short, though 

 frequently presented as a distinct argument, embryological 

 similarity, together with all else of value that can still be 

 salvaged from the wreck of the Mliller-Haeckel Law of Em- 

 bryonic Recapitulation, is, at bottom, identical with the gen- 

 eral evolutionary argument from homology. In the latter 

 argument we are directed to look beneath the modified surface 

 of the adult organism for surviving vestiges of the ancestral 

 type. In the former, we are bidden to go deeper still, to the 

 extent, that is, of descending into the very embryological 

 process itself, in order to discover lingering traces of the an- 

 cestral likeness, which, though now utterly deleted from the 

 transformed adult, are yet partially persistent in certain 

 embryonic phases. 



In sectioning a larval specimen of the fly-like termite-guest 

 known as Termitoxenia Heimi, Father Wasmann came across 

 a typical exemplification of this embryological atavism. In 

 the adult insect, a pair of oar-like appendages replace the 

 wings characteristic of the Diptera (flies) . These appendages 

 are organs of exudation, which elaborate a secretion whereof 



