THE EARLIEST KNOWN VERTEBRATES 19 
might be persuaded to yield a satisfactory an- 
swer. ‘The most direct way has been that of 
tracing back the history of animal life by means 
of fossil remains, but beyond a certain point 
this method cannot go, since, for reasons stated 
in various places in these pages, the soft 
bodies of primitive animals are not preserved. 
To supplement this work, the embryologist has 
studied the early stages of animals, as their de- 
velopment throws a side-light on their past 
history. And, finally, there is the study of the 
varied forms of invertebrates, some of which 
have proved to be like vertebrates in part of 
their structure, while others have been revealed 
as vertebrates in disguise. So far these various 
methods have yielded various answers, or the 
replies, like those of the Delphic Oracle, have 
been variously interpreted so that vertebrates 
are considered by some to have descended from 
the worms, while others have found their begin- 
nings in some animal allied to the King Crab. 
Every student of genealogy knows only too 
well how difficult a matter it is to trace a fam- 
ily pedigree back a few centuries, how soon the 
family names become changed, the line of de- 
