92 LIFE OP 



and Balfour has, since the first issue of the " Origin of 

 Species," grown into a coherent science, based on em- 

 bryology, was even then seen by Darwin to yield evidence 

 for his views. Examining very young animals, he found 

 that in very distinct races of dogs and horses the young 

 had by no means acquired their adult differences. He 

 compared pigeons of extremely various breeds twelve 

 hours after being hatched, and found their differences 

 incomparably less than in the full-grown birds. How 

 immensely morphological science has progressed since 

 Darwin directed investigation into this profitable line 

 would need a separate treatise to show ; but it is not too 

 much to say that embryology alone, without other evi- 

 dence, would now suffice to prove the doctrine of descent 

 with adaptive modification. 



Rudimentary organs, again, strange appearances, like 

 the presence of teeth in unborn whales and in the front 

 of the upper jaws of unborn calves, the rudimentary wings 

 of many insects, the rudimentary stamens or pistils of 

 many flowers, are all swept into the Darwinian net. 

 " Nothing can be plainer than that wings are formed for 

 flight ; yet in how many insects do we see wings so re- 

 duced in size as to be utterly incapable of flight, and not 

 rarely lying under wing-cases, firmly soldered together ? " 

 These phenomena are all explicable if descent with 

 modification is true. 



Approaching the close of his work, the author expressed 

 his doubts of being able to convert naturalists of long 

 standing to his views ; but based his main hopes on 

 young and rising men approaching these quesfions with- 

 out prejudices. He put some puzzling questions, however, 



