tions, even major works, dealing with some isolated aspect of disordered visual perception. The German language literature has been outstanding in such intimate and exciting studies of various facets of a clinical gem elaborately cut. Dr. K6lmel's monograph bears out these yiews. Without re­ sort to experimentation - for in such a project no animal model exists - the researcher has had to rely upon his clinical skills. Of vital importance was the information volunteered by the patient whose experiences are so bizarre, so unexpected as to exceed the victim's command of verbal expression. Being in essence purely subjective, their nature and indeed their very existence cannot be established unequivocally. Caveat auditor. Here is where the investigator's experience and clinical skill comes into play.