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1909. PATON, J. AIRMAN, Notes on Some Hybrid Tuberous 

 Solanums. Roy. Hort. Soc. Jour. 35 : 53-55. 



1909. PEARL, RAYMOND, A Note on the Degree of Accuracy of 

 Biometric Constants. Am. Nat. 43 : 238-240. 



1909. PEARL, RAYMOND, and SURFACE, FRANK M., Selection 

 Index Numbers and their Use in Breeding. Am. Nat. 

 43 : 385-400. 



1909. PEARL, RAYMOND,- and SURFACE, FRANK M., Data on the 

 Inheritance of Fecundity obtained from the Records of Egg 

 Production of the Daughters of "%00-egg " Hens. Maine 

 Agr. Exp. Sta. Bull. 166: (34 pp.), 13 figs. 



1909. PEARSON, KARL, Determination of the Coefficient of Cor- 

 relation. Science, n.s. 30 : 23-25. 



1909. PEARSON, K., On the Ancestral Gametic Correlations of 

 a Mendelian Population Mating at Random. Roy. Soc. 

 London Proc. 81 : 225-229. 



1909. PERRIRAZ, J., Etude biologique et biometrique sur Nar- 

 cissus angustifolius. Soc. Vaud. Sci. Nat. Bull. 45 : 153- 

 176. 



1909. PIPER, C. V., Alfalfa and its Improvement by Breeding. 

 A. B. A. Rep. 5:94-115. 



1909. PLATE, L., Darwinismus u. Landwirtschaft. 24 pp. 

 Parey, Berlin. 



1909. POWERS, H. J., Are Species Realities or Concepts Only? 

 Am. Nat. 43 : 598-610. 



1909. PRICE, H. L., and DRINKARD, W., Inheritance in Tomato 

 Hybrids. Plant World, 12 : 10-18, figs. 1-2. 



1909. PRICE, H. L., and DRINKARD, A. W., Inheritance in 

 Tomato Hybrids. Virginia Agr. Exp. Sta. Bull. 177 : 17- 

 53, 10 pis. Rev. (English) in Zeitsch. f. indukt. Abst.- u. 

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1909. RITTER, G., Uber discontinuierliche Variation im Organis- 

 menreiche. Bot. Centralbl. Beih. 251 : 1-29. 



1909. RITTER, W. E., The Hypothesis of "Presence and Ab~ 



