THE INFLUENCE OF THE ENVIRONMENT AMONG ANIMALS
AND PLANTS 325
(1) Observations show that environment and heredity are
complementary one to the other. (2) Abnormal stimuli may produce
almost any result, but (3) for each species there is a normal
environment, to certain elements in which marked responses may
be made, though (4) generally speaking sessile organisms are far
more responsive to differences in the environment than are
free-living organisms. (5) Among free-living species in a state
of nature closely related to man, modifications are not of great
importance in producing variations.