6 
GRAND DISCOVERIES OF LIFE 
all of the principal types of life is, doubtless, for other reasons, 
more apparent than real. Our taxonomic notions of class dis¬ 
tinctions are based mainly upon our familiarity with the land 
faunas about us, in a single branch which has come up to us 
from Cambric times. When the inferior types shall have been 
more equably considered it may be found that many taxonomic 
ranks will have to be raised. When this shall have been accom¬ 
plished the singularly isolated branches which have traversed the 
ages will be doubtless discovered to be as complex and as ramify¬ 
ing as that branch of which man is the crowning glory. 
Life’s discovery of the bottom of sea narrows vastly the infer¬ 
ential span of its existence that is a necessary consequence of the 
conception that life was already nine-tenths differentiated at the 
beginning of Cambric time. 
Of the many missing links in organic evolution, as disclosed 
by carrying the Darwinian theory to its logical conclusion, that 
of bridging the seeming bottomless chasm between the vertebrates 
and the invertebrates was always least responsive to revelation. 
This break long stood easily facile princeps among all difficulties. 
For half a century after the appearance of Darwin’s epoch-mak¬ 
ing work the derivation of the back-boned animals resolutely 
withstood all attempts at satisfactory solution. The primitive 
Amphioxis, a simple fish-like organism having a well defined 
notochord but no bones, was long believed to fill the gap, but it 
really served, as we now know, to obscure the facts rather than 
to elucidate them. Then, too, among zoologists generally the 
annelid theory was so long and so strong in the forefront as to 
crowd out all else. 
It is a singular fact that the paleontologists did not rise to the 
occasion and flash a ray of light into that dense darkness which 
the zoologists could not penetrate. The vast expansion of the 
trilobites in Cambric times should have at least aroused suspicion 
that the clue might be found in or near such a group. But the 
trilobites belonged to a class long since extinct, their internal 
structures were unknown, and their closest living kin was suppos¬ 
ed to be a horse-shoe crab. 
It remained for a demure professor of one of our lesser Ameri¬ 
can colleges to find the key. William Patten, of Dartmouth 
College, was especially interested in the embryology of the Arth¬ 
ropods, that great class comprising the insects, crustaceans, and 
