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INFORMATION TO SUBSCRIBERS 
Subscriptions at the rate of $5.00 per annum should be made payable 
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Sciences, Smithsonian Institution, Washington, D. C. Single numbers, $0.50. 
Past publications of the National Academy of Sciences are listed in these 
Proceedings, Volume III, pp. 743-753, December, 1917. In good part these 
publications are no longer available for distribution. Inquiries with regard 
to them should be addressed to the Home Secretary, National Academy of 
Sciences, Smithsonian Institution, Washington, D. C» 
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Single numbers may be obtained for fifty cents except where the sale of such 
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