Specificity of Streptococci Isolated from Patients with Skin Diseases: Studies on Pemphigus, Dermatitis Herpetiformis, Lupus Erythematosus and Erythema Multiforme11Abridgement of Thesis submitted to the Faculty of the Graduate school of the University of Minnesota in Partial fulfillment of the requirements of the degree of M.S. in Dermatology and Syphilology.