Those who are conversant with Albert A. Gray's large and comprehensive two volume work on "The Labyrinth of Animals" will little wonder that this clinician and investigator should subsequently be writing on problems pertaining to evolution. His extensive studies on the comparative anatomy of the intricate and delicate inner ear naturally led Gray to ponder over the problems of origin and variation. Then too his observations and contributions in the field of clinical otology, especially otosclerosis, afforded opportunity for reflection in the field of pathogenesis. Whether or not entirely in accord with the concept of Gray on tissue evolution and pathogenesis, one cannot but admire him for his spirit and industry in subjecting his clinical problems to scientific laboratory scrutiny.
From the beginning, Gray appears to have given thought to the manner in which the structure of plants and animals may have evolved in direct relationship to environment. He had