THE SYNTHETIC PHILOSOPHY AN ORGANON OF THE SCIENCES. 655 
which an unfolding structure becomes endowed with diverse functions. By virtue 
of the marvelous changes due to differentiation, two vital germs, apparently similar 
in nature, develop into two living beings widely dissimilar in form.and nature ; 
one may develop into the serpent which crawls in the dust, the other into the 
bird of-paradise which makes the forest glorious with its beauty. Integration and 
differentiation in organic evolution supplement each other. Without the former 
there would be no organic unity, but a mere assemblage of parts, each existing 
and acting fo itself. Without the latter there would be no specialization of struc- 
tures and functions, but a mere aggregation of parts. 
These principles, as worked out by Mr. Spencer, constitute the essential 
characteristics of evolution, which, as he has shown, applies to all orders of phe- 
nomena, whether organic or inorganic, as the universal law of the redistribution 
of matter, force and motion. We may define thus: Avolution ts an orderly and 
successive series of changes from a simple and homogeneous state to one that 1s complex 
and heterogeneous, through the twofold process of integration and differentiation conse- 
quent upon a loss of motion. 
It has been said by its opponents that Evolution is only a hypothesis. This 
we admit; but no one acquainted with the logic of science would argue from this 
that it should be regarded as false. If sustained by facts, if it explains what 
would otherwise remain unexplained, while, at the same time, it is not contra- 
dicted by any known principle of nature, then a scientific hypothesis is to be 
regarded as true. Science is largely built upon hypotheses of this character, such 
as the undulatory theory of light, and the molecular and atomic theories of mat- 
ter. As to absolute certainty, this is beyond the powers of inductive investiga- 
tion, as we are taught by the ablest writers on the logic of science. ‘‘ The theory 
of Spencer, says Prof. Jevons in his work on Zhe Principles of Science, ‘‘is to 
some extent hypothetical, just as all the theories of physical science are to some 
extent hypothetical, and open to doubt. Judging from the immense numbers 
of diverse facts which it harmonizes and explains, I venture to look upon the 
theory of evolution in its main features as one of the most probable hypotheses 
ever proposed.” 
Mr. Spencer, by an induction of facts never before equaled for the variety 
and extent of learning which they display, has shown how all those phenomena 
which involve questions of genesis or succession find their explanation and 
organizing law in Evolution. That the solar system had a nebular genesis is 
now, we may say, universally received by astronomers According to this theory 
the system had its origin out of a homogeneous and incandescent vapor, which 
rotating about a center passed through successive changes consequent upon a 
dissipation of motion in the form of heat. As the rotating mass cooled, there 
was integration; when this process had reached a certain stage, rings were thrown 
off from the more rapidly revolving equatorial regions, which gathered into 
planets. Here was differentiation. The central and larger portion being less 
condensed on account of its retained heat, formed the sun. Here we have evo- 
RY 
