A transmissible strain of sarcoma (Strain 13) is described that took its origin in a chicken inoculated with leukosis of Strain 1. The virus of Strain 13 produces sarcoma in the breast muscle injected with it and after intravenous inoculation it produces diffuse sarcomatosis of the spleen, bone marrow, and several other organs.
The available evidence suggests that Strain 13 is caused by a single virus with ability to produce diffuse endothelial growth in the blood-forming organs associated with extensive hematomata, and erythroblastic proliferation.
The strain can be readily transmitted by material free from live cells and preserved by drying. As small amounts of blood as 0.00001 cc. from chickens with sarcomatosis of the internal organs transmit Strain 13 by the intravenous route.
By implantation sarcoma of Strain 13 can be transferred to chickens that are resistant to repeated inoculations with leukotic viruses.