[198] Shull, A. F., and Ladoff, S., Science, 1916, xliii., 177.

[199] Steinach, E., Zentralbl. f. Physiol., 1910, xxiv., 551; Arch. f. d. ges. Physiol., 1912, cxliv., 72.

[200] For the literature on the subject the reader is referred to Morgan, T. H., Sturtevant, A. H., Muller, H. J., and Bridges, C. B., The Mechanism of Mendelian Heredity. New York, 1915.

[201] Mendel, G., “Experiment in Plant-Hybridiza­tion,” translated in W. Bateson’s classical book on Mendel’s Principles of Heredity. Cambridge, 1909.

[202] The reader will find a critical discussion of the presence and absence theory on page 220 of Morgan, Sturtevant, Muller, and Bridges, The Mechanism of Mendelian Heredity. New York, 1915.

[203] Sutton, W. S., “The Chromosomes in Heredity,” Biol. Bull., 1904, iv., 231.

[204] Morgan, T. H., Sturtevant, A. H., Muller, H. J., and Bridges, C. B., Mechanism of Mendelian Heredity. New York, 1915, p. 26.

[205] Morgan, T. H., Sturtevant, A. H., Muller, H. J., and Bridges, C. B., The Mechanism of Mendelian Heredity. New York, 1915.

[206] Bateson, W., loc. cit., p. 157.

[207] The number of hereditary characters examined to test the theory was over 130.