DR. THOMAS M. RIVERS discussed the possibilities that viruses represent a transition between living and non-living matter, at a meeting of the New York Academy of Medicine on March 29. A report of the meeting issued by Science Service mentions that the discovery of bacteria was formerly held by some men of science to indicate the origin of life in the world. Many workers now believe this to be the case for viruses. Dr. Rivers discussed the retrograde and the evolutionary vital theories, and also the non-vital autocatalytic ideas of several students of the problem. He pointed out that the weakness of these conceptions is that viruses may not all be similar, and such a plastic group may well embrace all the forms mentioned.