The object of this paper is to place on record some work which has been done during the past fourteen months in the laboratories of the Cardiff City Mental Hospital. This work, which is in the nature of animal inoculation experiments, was done with a view to detecting the presence of any filter-passing organisms which might be present in cases of schizophrenia. The justification for this line of research depends upon the suggestions that have been made by American and Continental writers that there are many striking points of resemblance between epidemic encephalitis and schizophrenia. In this country, Farran-Ridge has pointed out the striking similarity of the motor phenomena in certain cases of these two conditions. He draws attention particularly to fluctuation in body-weight, blepharoclonus, pruriginous phenomena, chewing movements, greasy face, respiratory disorders and choreiform manifestations. It has been suggested that these symptoms may be due to involvement of the basal ganglia. This being so, there is primâ facie evidence that some cases of both encephalitis and schizophrenia are the outward manifestations of similar disease-processes. In the case of encephalitise, vaditi, Loewe, Hirschfield and Straus and others have done work which suggests the existence of an ultra-virus of variable virulence which may exist in the saliva, the central nervous system, herpetic vesicles and elsewhere. If, therefore, these premises are correct, it would be valid to search for a similar virus in schizophrenia.