are affected and hence the germ cells themselves. Certainly such interpretations, while the merest speculations, are hard to deny from the known facts.
In such theoretical discussions of the nature of germ plasm and the potency of factors biologists are very apt to lose sight of the true historical purpose of the hypothesis of the inheritance of acquired characters. The real question to be answered first is whether or not acquired characters actually appear in following generations to such an extent as to make real contributions to the course of evolution. Even if the so-called inheritance is really a change in potency due to the direct action of stimuli on the germ plasm, nevertheless, the Lamarckian factor may be a real factor. We have not explained away any process by showing the method of its operation. The real question to be decided should be stated broadly. Do new habits and new environment produce changes in form which are of importance in organic evolution? "While a final answer can not at present be given to the question, it may safely be stated that a renewal of interest in Lamarck's factor is justified by the results of recent research.