The Section of Psychology of the American Association for the Advancement of Science

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Abstract
500 mouse brains were ground with sand and 0.05 [image] NaCl solution added to make a total volume of 3,500 ml. After settling overnight, the supernatant extract was siphoned off and shaken with 2/3 by volume of ether. The bottom layer was collected and 1/2 by volume of sat''d. (NH4)2SO4 was added. The precipitate formed was collected, washed with 1/3-sat''d. (NH4)2SO4, and finally with distilled water. The aqueous extract was concentrated by ultrafiltration as described by Seibert, washed on the filter paper with dist. water until free from salt or ether, and finally fractionated in an air-driven high-speed quantity centrifuge at 11,000 and 22,000 r.p.m. All operations were performed at < 8[degree] C. The prepns. retained 30-50% of the original activity. The sedimentation constant of the virus was found to be 160-170 X 10-13 and the diffusion constant observed was D20 = 0.27-0.33 X 10-7.