REPORT OF THE PRESIDENT, 1920. 



23 



List of publications issued during the year — continued. 



No. 290. Clements, Frederic E. Plant Indicators: The Relation of Plant Communities to 

 Processes and Practice. Octavo, xvi +3SS pages, 92 plates, 25 figures. 



No. 292. Weaver, John E. Root Development in the Grassland Formation: A correlation of 

 the Root Systems of Native Vegetation and Crop Plants. Octavo, 151 pages, 

 2 maps, 23 plates, 39 figures. 



No. 294. Mortensen, Th. Studies in the Development of Crinoids. Paper from the Depart- 

 ment of Marine Biology of the Carnegie Institution of Washington. Vol. XVI. 

 Quarto, iv+94 pages, 28 plates, 10 figures. 



No. 296. Key, Wilhelmine E. Heredity and Social Fitness: Study of Differential Mating in a 

 Pennsylvania Family. (Paper No. 32, Station for Experimental Evolution of 

 the Carnegie Institution of Washington.) Octavo, 102 pages, 2 charts, 2 figures. 



No. 297. MacDougal, Daniel T. Hydration and Growth. Octavo, vi +176 pages, 52 figures. 



No. 298. Nichols, Edward L., and H. L. Howes, in collaboration with Ernest Merritt, D. T. 

 Wilber, and Frances G. Wick. Fluorescence of the Uranyl Salts. Octavo, 241 

 pages, 1 plate, 11 figures. 



The following table shows the amounts received 



tions and Value of from subscriptions to the Index Medicus, from 



an . goles of Year Books, and from sales of all other 



publications for each year since the foundation of the Institution : 



Table showing sales of publications. 



At the end of the fiscal year there are on hand 98,412 volumes 

 of miscellaneous publications and Year Books, having a sale 

 value of $288,930.85; also 37,593 numbers of the Index Medicus, 

 having a sale value of $20,723.50. The total sale value of pub- 

 lications on hand is therefore $309,654.35. It is fitting to add 

 that since the foundation of the Institution there have been 

 distributed, chiefly by gifts to libraries and to authors, but to a 

 noteworthy extent also by sales, a total of 209,316 volumes of 

 pubHcations of the Institution. 



