Abstract
The results are described of further studies on a virus found in the roots of certain normal-looking plants. It is shown that the virus is a contamination arriving from outside sources. The virus has been detected in the sludge at the bottom of the water tanks, and the experimental evidence shows that it is water-borne to the soil whence it reaches the roots of the plants. Experiments to test the possibility that the virus is also air-borne have so far proved negative. The virus is exceedingly resistant, it can be completely desiccated and remains infective in the dry state for many weeks. It is also unaffected by alcohol and is still infective after being stored in absolute alcohol for 6 months. The virus is thought to be a transitional stage between a pathogen and a non-pathogen.