102 THE AMERICAN MIDLAND NATURALIST 
complicated organization as that which is displayed by the 
sun and its attendant bodies ever came into existence by 
accident. Beyond possibility of question the story of the 
birth of the system would be revealed in its organization and 
forces, were man only able to read that record. But in spite 
of the fact that we can give no positive definite interpreta- 
tion of the remaining traces of the earth’s beginning it is 
necessary, in order to carry on investigation, to form hypo- 
theses to explain them. It is also important that we study 
these hypotheses carefully and note the various ways in which 
they may enter into the doctrines and ideas of modern science. 
Not a few of the principles of geology, astronomy, and even 
biology rest upon some hypothesis of the earth’s origin, and 
have no greater strength than that of the hypotheses on which 
they are founded. 
1.—The Laplachian Hypothesis. 
It is the almost universal opinion among astronomers that 
the solar system was evolved from some sort of a nebula. 
Until comparatively recently most of them accepted a special 
hypothesis advanced in the latter part of the eighteenth cen- 
tury. by the great French mathematician Laplace. So general 
was the acceptance of Laplace’s idea that it came to be known 
as the “Nebular Hypothesis,” without consideration of the 
fact that there were several other hypotheses which also sup- 
posed that the solar system was derived from a nebula. This 
explanation of Laplace’s was supposed to offer a thoroughly 
satisfactory interpretation of the existing evidence as to the 
origin of the solar system, and therefore of the earth. But 
with the advance of geological and astronomical knowledge it 
beeame evident that the Laplacian hypothesis did not satis- 
factorily explain the origin of the earth, and that a new inter- 
pretation was necessary. 
The Laplacian, or as it is popularly called, the Nebular 
Hypothsis has, however, gained so firm a foothold in literature 
and general knowledge that we must give it-a careful survey 
before passing on to newer and more satisfactory ideas. La- 
place supposed that the solar system was descended from an 
immense, rotating ball of gas which extended beyond the 
orbit of the outermost planet—that is, which had a diameter 
