in childhood should have children whose legs, at birth, appeared deformed in the same manner; then there would be a distinct case of the transmission of an acquired characteristic. "The precise question," as Professor Thomson words it, "is this: Can a structural change in the body, induced by some change in use or disuse, or by a change in surrounding influence, affect the germ-cells in such a specific or representative way that the offspring will through its inheritance exhibit, even in a slight degree, the modification which the parent acquired?" He then lists a number of current misunderstandings, which are so widespread that they deserve to be considered here.
(1) It is frequently argued (as Herbert Spencer himself suggested) that unless modifications are inherited, there could be no such thing as evolution. Such pessimism is unwarranted. There is abundant explanation of evolution, in the abundant supply of germinal variations which every individual presents.
(2) It is common to advance an interpretation of some observation, in support of the Lamarckian doctrine, as if it were a fact. Interpretations are not facts. What is wanted are the facts; each student has a right to interpret them as he sees fit, but not to represent his interpretation as a fact. It is easy to find structural features in Nature which may be interpreted as resulting from the inheritance of acquired characters; but this is not the same as to say and to prove that they have resulted from such inheritance.
(3) It is common to beg the question by pointing to the transmission of some character that is not proved to be a modification. Herbert Spencer cited the prevalence of short-sightedness among the "notoriously studious" Germans as a defect due to the inheritance of an acquired character. But he offered no evidence that this is an acquirement rather than a germinal character. As a fact, there is reason to believe that weakness of the eyes