92 EVOLUTION, OLD AND NEW. 



The compromise which he thought fit to put before 

 the puUic was that " Each species has a type of which 

 the principal features are engraved in indelible and 

 eternally permanent characters, while all accessory 

 touches vary." * It would be satisfactory to know 

 where an accessory touch is supposed to begin and end. 



And again : — 



" The essential characteristics of every animal have 

 been conserved without alteration in their most im- 

 portant parts. . . . The individuals of each genus still 

 represent the same forms as they did in the earliest 

 ages, especially in the case of the larger animals " (so 

 that the generic forms even of the larger animals prove 

 not to be the same, but only 'especially' the same 

 as in the earliest ages), t 



This transparently illogical position is maintained 

 ostensibly from first to last, much in the same spirit 

 as in the two foregoing passages, written at intervals 

 of thirteen years. But they are to be read by the 

 light of the earlier one — placed as a lantern to the 

 wary upon the threshold of his work in 1753 — to 

 the effect that a single, well substantiated case of 

 degeneration would make it conceivable that all 

 living beings were descended from a single common 

 ancestor. If after having led up to this by a remorse- 

 less logic, a man is found five-and-twenty years later 

 still substantiating cases of degeneration, as he has 

 been substantiating them unceasingly in thirty quartos 

 during the whole interval, there should be little 



• Tom. xiii. p. ix. 1765. f Sup. torn. v. p. 27, 1778. 



