234 THE COMING OF AGE OF VII 
existent, and that the contrary doctrine is now 
universally accepted and taught. 
But there were other cases in which the wide 
structural gaps asserted to exist between one group 
of animals and another were by no means fictitious ; 
and, when such structural breaks were real, Mr. 
Darwin could account for them only by supposing 
that the intermediate forms which once existed 
had become extinct. Ina remarry passage he 
says— 
“We may thus account even for a distinctness 
of whole classes from each other—for instance, of 
birds from all other vertebrate animals—by the 
belief that many animal forms of life have been 
utterly lost, through which the early progenitors 
of birds were formerly connected with the early 
progenitors of the other vertebrate classes.” * 
Adverse criticism made merry over such sugges- 
tions as these. Of course it was easy to get out of 
the difficulty by supposing extinction; but where 
was the slightest evidence that such intermediate 
forms between birds and reptiles as the hypothesis 
required ever existed ? And then probably followed 
a tirade upon this terrible forsaking of the paths 
of “ Baconian induction.” 
But the progress of knowledge has justified Mr. 
Darwin to an extent which conla hardly have 
been anticipated. In 1862, the specimen of 
Archeopteryx, which, until the last two or three 
1 Origin of Species, p. 431. 
