No. 383.] VARIATION VERSUS HEREDITY. 827 
for each series, or race of organisms, breeding and developing 
together under like conditions. 
If varying brings about modifications which are beneficial, 
then that which promotes varying must be an advantage. But 
in order to originate a species, varying is checked, and it is 
only as natural selection checks, transmits, and preserves, /ess 
variably, the characters acquired by variation that the origin 
of species results. 
Thus we discover that the application of this hereditary 
principle to organisms, as a fundamental characteristic of liv- 
ing processes, makes it necessary to assume that evolution does 
not work in harmony with it ; but only by checking, antagoniz- 
ing, and violating heredity is any progress attained. 7 
On the other hand, on the view that variation is the ulti- 
mate principle of all vital phenomena and is operative (as it is 
known to be) prior to experience, evolution becomes the full- 
est expression of life, and heredity and relative uniformity of 
reproduction the most natural expressions of the economical 
adjustment of living organisms to the limitations of environ- 
ment. Evolution, in other words, takes place, naturally, as 
fast as the construction of organization and adjustment to 
environment furnish the possible medium for its expression. 
On this hypothesis evolution becomes as natural and universal 
a process for organic bodies as gravitation is for physical 
bodies. 
Fourthly : According to the current philosophy of evolution, 
struggle for existence is assumed to be a most important factor 
in determining the course of “ selection,” or: “ preservation,” 
by which advance is made. This struggle for existence is 
assumed to operate in the way of overcoming competitors for 
the same sources of good ; and fitness to survive is measured 
by the capacity to grow big. 
This theory, that measure of success is amount of food an 
organism can assimilate, that growing fat is evidence of fitness 
to survive, is consistent with the belief that repetition of the 
characters of ancestors, or heredity, is the primary law of 
organisms; and it is this philosophy which would lessen com- 
petition as a means of promoting progress. 
