Viral and Bacteriologic StudiesThe nature of these illnesses has suggested to most a viral etiology, but, despite intensive efforts to implicate such an agent, results have been meager. Cerebrospinal fluid, feces, throat washings, acute-phase serums and blood clots have been inoculated by a variety of routes into many different laboratory animals and various tissue-culture systems. Despite the frequent use of blind passages, attempts to infect the following animals have thus far proved futile: sucklingl,8,10,14,15,26,29–31,34 and adult mice8,14,26,29,31; guinea pigs with8 and without cortisone10,26,31; hamsters8,10,14,26; rabbits26,31; rats with and without cortisone15; ferrets8; and cynomologus . . .