It appears definitely established that herpes simplex, irrespective of its clinical variety, is a generalized specific infectious disease with localizing symptoms on the skin (herpetic eruption) and in some instances, particularly herpes progenitalis, in the nervous system. At the present time, this conception of the etiology of simple herpes is based on experimental observations in both the human subject and certain laboratory animals, the rabbit in particular, in whom the active agent, a filtrable virus under certain conditions, produces severe kerato-conjunctivitis and in some instances, varying with the virus or its source, fatal encephalitis. Although demonstrated many years ago, only recently has it been generally accepted that this disease is both auto-inoculable and heteroinoculable. Teissier, Gastinel and Reilly,1after lightly scarifying the forearms of patients presenting simple herpes and others not attacked with simple herpes, inoculated all of them with herpetic exudate. There were thirteen "takes" in sixteen auto-inoculation