Day-To-Day Variations in the Erg of Humans and Rabbits* *From the Neurosensory Center (Paper No. 6) and the ERG laboratory of the Department of Ophthalmology (Dr. Burian), College of Medicine, State University of Iowa. The Neurosensory Center is supported by Program-Project grant B-3354 of the National Institute of Neurological Diseases and Blindness. This work was supported by grant B-349 (C8) to Dr. H. M. Burian by the National Institute of Neurological Diseases and Blindness. Presented at the annual meeting of the Midwestern Section of the Association for Research in Ophthalmology, Chicago, 1962.