Abstract
The association of a previously described enzyme which splits adenosine triphosphatase with the particles of myxoviruses was confirmed by chromatography on diethylaminoethyl cellulose and density gradient centrifugation of prepurified preparations of Newcastle disease, Sendai and A-2 influenza viruses as well as of the enzyme peculiar to the tissue. The enzyme is able to split adenosine triphosphatase also.