Gates .— The Trisomic Mutations of Oenothera . 563 
Gates, R. R. ( 1922 ) : Some Points on the Relation of Cytology and Genetics. Journ. of Heredity, 
xiii. 75-6. 
- ( 1923 ) : A Peculiar Type of Variab lity in Plants. Journ. Genet., xiii. 13-45, Pigs. 24. 
- and Thomas, Nesta (1914); A Cytological Study of Oenothera mut. lata and 
Oe. mut. semilaia in Relation to Mutation. Quart. Journ. Micro. Sci., lix. 523-71, 
Pis. 35 - 7 , Figs- 4 - 
Hance, Robert T. ( 1918 ) : Variations in the Number of Somatic Chromosomes in Oenothera 
scintillans , de Vries. Genetics, iii. 225—75, Pis. 7, Figs. 5. 
Lehmann, Ernst ( 1922 ) : Die Theorien der Oenothera- forschung. Jena: Fischer, pp. 526, 
Figs. 207. 
Lutz, A. M. ( 1908 ) : Chromosomes of the Somatic Cells of the Oenotheras. Science, N. S., xxvii. 
335 * 
-1 912 ): Triploid Mutants in Oenothera . Biol. Centralbl., xxxii. 385-435, Figs. 7. 
-- ( 1916 ): The Production of 14 +-chromosome Mutants by 14-chromosome Oeno¬ 
thera Lajnarckiana. Science, N.S. xliii. 291-2. 
- ( 1916 ): Oenothera Mutants with Diminutive Chromosomes. Amer. Journ. B'd., iii. 
502-26, PI. 24, Figs. 7. 
- ( 1917 ): Fifteen- and Sixteen-chromosome Oenothera Mutants. Ibid., iv. 53—111, 
Figs. 9. 
MacDougal, D. T., Vail, A. M., Shull, G. H., and Small, J. K. ( 1905 ) : Mutants and 
Hybrids of the Oenotheras. Carnegie Publ., No. 24, pp. 57, Figs. 13, Pis. 22. 
van Overeem, Caspar ( 1920 ) : UberFormen mit abweicbender Chromosomenzahl bei Oenothera. 
Dissertation. Beih. z. Bot. Centralbl., xxxviii, pp. 47, Pis. 6. 
- ( 1922 ): Same title. Ibid., xxxix, pp. 1—So, Pis. 15. 
Schaffner, J. H. ( 1918 ) : The Expression of Sexual Dimorphism in Heterosporous Sporophytes- 
Ohio Journ. Sci.,xviii. 101-25. 
Tischler, G. ( 1921 - 1922 ): Allgemeine Pflanzenkaryologie. Berlin : Borntrager, pp. 899, 
Figs. 406. 
de Vries, Hugo ( 1909 ) : The Mutation Theory, vol. i, pp. 5S2, Figs. 119. Trans. Farmer and 
Darbishire. 
---( 1913 ): Gruppenweise Artbildung, unter spezieller Berucksichtigungder Gattung 
Oenothera. Gebriider Borntrager, Berlin, pp. 365, Figs. 121. 
- ( 1916 ) : New Dimorphic Mutants of the Oenotheras. Bot. Gaz,, lxii. 249-80, 
Figs. 5. 
- ( 1918 ) : Mutations of Oenothera snaveolens , Desf. Genetics, iii. 1-26, Figs. 4. 
- ( 1919 ) : Oenothera Lapiarckiana mut. simplex. Per. Deut. Bot. Gesellsch., 
xxxvii. 65-73. 
explanation of PLATE XI. 
Illustrating Professor Gates’s paper on the Trisomic Mutations of Oenothera. 
All figures were drawn with a j^-inch Koristka immersion lens N.A. 1*30 and compensating 
ocular 12, and reduced one-fourth in reproduction, giving a magnification of 2,250 diameters. 
Fig. 1. Pollen mother-cell in diakinesis, showing five ring-pairs of chromosomes and five single 
chromosomes. 
Fig. 2. Another cell at the same stage, showing five rings. 
Fig. 3. Multipolar spindle stage, showing 15 chromosomes, including a looped ring. 
Fig. 4. Another cell at the same stage, showing a looped ring. 
Fig. 5. Heterotypic spindle in early anaphase, showing the odd chromosome e. 
Fig. 6. Heterotypic bipolar spindle, showing a persistent ring chromosome. 
Fig. 7. Heterotypic anaphase, showing 15 chromosomes, seven of them approaching one pole, 
five the other, and three lagging behind. 
Fig. 8. Heterotypic telophase with probably eight chromosomes in one daughter nucleus, six in 
the other, and one left behind in the cytoplasm. Most of the chromosomes show their split character 
at this time. 
