654 @ KANSAS CITY REVIEW OF SCIENCE. 
or development. The growth of a plant or an animal from the simple germ ‘‘is 
the typical specimen of a phenomenon which rules through the whole course 
of the history of man and society—increase of function through expansion and 
differentiation of structure by internal forces.” It will then be best to define and 
illustrate the fundamental characteristics of Evolution from the standpoint of 
organic phenomena. 
1. Zhe homogeneous :—Embryology has revealed the fact that the complex 
animal organism is developed from a simple germ which, because of a sameness 
o° structure, is characterized by the term homogeneous. ‘‘ However much,’’ says 
Beale, ‘‘organs and their tissues in the fully formed state may vary as regards the 
character, properties and compositions of the formed material, all were first in 
the condition of clear, transparent, structureless living matter.” But this homo- 
geneous, structureless protoplasm is unstable, and must therefore differentiate 
itself, or develop into an unlikeness of parts, because of the vast amount of locked 
up energy which it contains. Hence, it assumes a dynamic relation to itself, in 
order that it may unfold into its higher self, and realize the ideal of growth and 
development stamped upon its inmost constitution, and which is but the full 
unfolding of the promise and potency enfolded in the original germ. 
2. The heterogeneous:—The final state into which the homogeneous and 
structureless matter of life unfolds is characterized as heterogeneous. ‘This final 
state, in contrast to the primitive simplicity out of which evolution arises, is char- 
acterized by a stiuctural difference among the coéxistent parts which become 
endowed with diverse functions. In the primitive homogeneous state there is no 
definite and coherent relation among the parts. In the final heterogeneous state, 
sameness has developed into diversity, simplicity into complexity, in which there 
is a definite and coherent relation among the parts. 
The vital movement by which life passes from this ariMGue simplicity to its 
final complexity is a doubie movement, and is expressed by the terms cnéegration 
and differentiation. . 
3.  JLntegration :—By integration is meant in Evolution the process by which 
the different parts of a structure or organsm are knit together into organic unity 
through their mutual dependence and codperation. The degree of coherency 
and dependence among the different parts of an evolved structure is determined 
by the degree of complexity and specialization of functions. An increasing 
specialization among the functions brings with it an increasing efficiency, and, at 
the same time, an increasing dependency and coherency, for the reason that as 
each organ becomes more specialized, it is less able to perform any other than its 
own allotted function. Some living beings, as the am@éba, are so low down in the 
scale of life that they have no specialization of parts. Foot, head and stomach 
are extemporized for the occasion. Integration is consequent upon a loss of mo- 
tion, so that the different parts are allowed to come into combining and coépera- 
tive relations. 
4.  Differentiation:—By differentiation is meant in Evolution the process by 
