STUDIES ON OAT BREEDING. 3 



the appearance of Johann sen's work numerous other investi- 

 gators have studied the same problem in other organisms. In 

 1908 Jennings' pubHshed his results on the selection within 

 pure lines of Paramecium. In this extensive work he was able 

 fully to confirm Johannsen'si results. Tower^ selected for inten- 

 sity of color in chrysomelid beetles for 12 generations with- 

 out obtaining any permanent result. East and Hayes' found that 

 selection to increase the number of leaves on self-fertilized to- 

 bacco plants gave no results. Hutcheson" has recently shown 

 that thirteen years of selection to increase the yield of pure lines 

 of wheat have resulted in no increase. Von Riimker' and his 

 students have also pointed out that seven years of selection in 

 pure lines of wheat have not changed the characters studied. 



These and ^many other investigations along similar lines have 

 tended to confirm Johannsen's theory and even to extend it to 

 the results of cross-fertilization between individuals homozy- 

 gous for the factors in question.^ 



On the other hand Castle' in a number of recent papers has 

 taken exception to the pure line theory. He maintains that 

 selection is able to change the unit characters or factors. As 



^Jennings, H. S. Heredity, Variation and Evolution in Protozoa, II. 

 Proc. Amer. Phil. Soc, Vol. XLVII, No. igo, pp. 393-546, 1908. 



*Tower, W. L. An Investigation of Evolution in Chrysoimelid Beetles 

 of the Genus Leptinotarsa. Carnegie Inistitution of Washington Publica- 

 ti'on iNo. 48, pp. 320, 1906. 



■^East, E. M. and Hayes, H. K. A Genetic Analysis of the 'Changes 

 Produced by Selection in Experiments with Tobacco. Amer. Nat., Vol. 

 XLVIII, pp. 5-48, 1914. 



"Hutcheson, T. B. Thirteen years of Wheat Selection. Amer. Nat., 

 Vol. XLVIII, pp. 459-466. 



'V. Riimker, K., Lerdner, R. und Alexandrowitsch, J. Die Anwendung 

 einer neuer Methode zur Sorten und Linienpriif ung bei Getreide. Zeit. f . 

 Pfianzenzucht. Bd. 2, pp. 189-232, 1914. 



•^Cf. Pearl, R. The Inheritance df Fecundiity in the Domestic Fowl. 

 Amer. Nat., Vol. XLV, pp. 321-345, 1911. Also The Mode of Inheritance 

 of Fecundity in the Domestic Fowl. Jour. Exper. Z06I., Vol. 13, pp. 

 153-268, 1912. 



"Castle, W. lE. The Inconsistency oi Unit Characters. Amer. Nat., 

 Vol. XLVI, pp. 352-363, 1912. 



and Phillips. Piebald Rats and Selection. Carnegie Insti- 

 tution of Washington Publication No. 195, 1914. 



Pure Lines and Selection. Journ. of Heredity, Vol. 5, pp. 



93-97, 1914- 



