If I have appeared at times overcritical concerning the application of genetics to pathology, it is not because I do not sympathize with the attempts that have been made to apply genetics to pathology. I realize, of course, that from the nature of the case much of this work is pioneer work, where rough and ready methods have often to be resorted to. So long as this is kept in view, no harm can be done in attempting to find how far Mendel’s principles can apply to heredity in man. But I want to enter a protest against the danger of premature conclusions drawn from insufficient evidence. In our enthusiasm in applying Mendel’s laws, we should be careful not to compromise them.