Quote by August Weismann
"Hereditary material is immutable in its essence, mutable in its expression."
"Hereditary material is immutable in its essence, mutable in its expression."
"The struggle for existence holds as much in the future as it has held in the past."
"Natural selection is the only true guiding force in the development of organic life."
"Acquired characteristics cannot be inherited; only those traits present in the germ cells pass to offspring."
"Evolution is not a theory of chance, but of necessity."