AGE OF CORAL REEFS. 199 
them. The succession of fossil Corals has been 
found in the rocks by the geologist, — the embry- 
ologist has followed the changes in the growth 
of the living Corals, — the zodlogist has traced 
the geographical distribution and the structural 
relations of the full-grown animals; but it is 
only after the results of their separate investi- 
gations are collected and compared that the 
coincidence is perceived, and all find that they 
have been working unconsciously to one end. 
These thoughts in Nature, which we are too prone 
to call simply facts, when in reality they are the 
ideal conception antecedent to the very existence 
of all created beings, are expressed in the objects 
of our study. It is not the zodlogist who invents 
the structural relations establishing a gradation 
between all Polyps, — it is not the geologist who 
places them in the succession in which he finds 
them in the rocks, —it is not the embryologist 
who devises the changes through which the living 
Polyps pass as he watches their growth; these 
investigators only read what they see, and, when 
they compare their results, it is found that they 
all tell the same story. He who reads most cor- 
rectly from the original is the best naturalist. 
What unites all their investigations, and makes 
them perfectly coherent with each other, is the 
coincidence of thought expressed in the facts 
themselves. In other words, it is the working 
