That physiology is the basis of scientific medicine is generally recognized. Medical students are taught that physiologic processes and the known laws governing them, form the foundation of our knowledge of the pathologic conditions with which we have to deal,—a criterion of the value of clinical observation; the base-line from which we are to estimate every real or apparent deviation from the normal functions of the human body. More especially is this true as regards ophthalmology, in many respects the most scientific department of medicine. Nevertheless, there have appeared in our ophthalmic literature, during the past five years, a number of theories which, when critically analyzed have little or no substantial scientific foundation.
While it is true that our knowledge of ocular physiology is incomplete, yet those physicians whose educational training has disciplined their minds to act logically; to habitually analyze the evidence presented; to refer phenomena if possible to