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Points from Foregoing Letters

Nature volume 139, page 290 (13 February 1937) | Download Citation



PROF. E. M. FRAENKEL and Dr. C. A. Mawson report that although they are able to deposit the agent of the Rous fowl sarcoma by centrifugation at 15,000 r.p.m., they are unable to correlate the cancer-producing activity of the extracts and concentrates with the number of ultra-microscopic particles present, and suggest that only a fraction of the visible particles are associated with carcinogenic activity. They have been unable to obtain tumours by injection of acetone extracts of fresh or dried tumour tissue, but the residue left after the extraction of dried powder retains its carcinogenic properties.

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