Any attempt at a scientific explanation of the phenomenon of crystal seering, to use an irregular but comprehensive term, would perhaps fall short of completeness, and certainly would depend largely upon the exercise of what Professor Huxley was wont to call the scientific imagination. The reasons for this are obvious. We know comparatively little about atomic structure in relation to nervous organism. We are informed to a certain degree upon atomic ratios; we know that all bodies are regarded by the physicist as a congeries of atoms, and that these atoms are centres of force.'