﻿474 



BOTANICAL GAZETTE 



21. Mottier, D. M., Heterotypic chromosomes. Box. Gaz. 40:171-178. 

 1005. 



22. , The development of the heterotypic chromosomes in pollen mother 



cells. Ann. Botany 21:309-349. 1911. 



23. , Mitosis in pollen mother cells in Acer Negundo L. and Staphylea 



trifolia L. Ann. Botany 28: 115-135. 1914. 



24. Mottier, D. M., and Nothnagel, Mildred, The development and 

 behavior of the chromosomes in the first or heterotypic mitosis of pollen 

 mother cells of Allium cernuum Roth. Bull. Torr. Bot. Club 40: 555- 

 505- IQI3- 



25. Overton, J. B., tiber Reduktionsteilung in den Pollen Mutterzellen 

 einigen Dikotylen. Jahrb. Wiss. Bot. 42:121-153- 1005. 



26. , On the organization of the nuclei in the pollen mother cells of 



certain plants with especial reference to the permanence of the chromo- 

 somes. Ann. Botany 23:19-63. 1909. 



27. Rosenberg, O., Uber die Reduktionsteilung im Droserai Neiddel. Stock- 

 holms Hogs. Bot. Inst. p. 13. 1904. 



28. Sharp, L. W., Somatic chromosomes in Vicia. La Cellule 29:297-333. 



29. Stout, A. B., The individuality of the chromosomes and their arrangement 

 in Carex aquatilis. Arch. Zellforschung 9: 114-141. 1912. 



30. Strasburger, E., Reduktionstheilung. Sitzungsber. Konigl. Preus. 

 Akad. Wiss. 18:587-614. 1904. 



31. , Typische und allotypische Kernteilung. Jahrb. Wiss. Bot. 42:1- 



70. 1905. 



32. Yamanouchi, S., Sporogenesis in Nephrodium. Bot. Gaz. 45:7~3 I - 

 1908. 



33. , Chromosomes in Osmunda. Bot. Gaz. 49:1-13. 1910. 



EXPLANATION OF PLATES XXVIII-XXX 

 All figures were drawn with the aid of a Spencer camera lucida with Bausch 

 and Lomb fa immersion and ocular 12, except figs. 1-11 inclusive, which 

 were drawn with Bausch and Lomb tV immersion and ocular 12. Magni- 

 fication of figs. 1 -11 inclusive X3500; all others X2650. The plates are 

 reduced to two-thirds the original size. 



PLATE XXVIII 



Fig. i.— Late telophase of the last division of the sporogenous tissue, 

 showing the anastomoses and the beginning of vacuolization along the median 

 longitudinal axis. 



Fig. 2.— A later stage, most of the chromosomes being vacuolate. 



Figs. 3, 4— Early stages of the pollen mother cells, which consist of 

 ladder-like structures that arose by vacuolization of the chromosomes; some 

 of the chromosomes still entire, owing to unevenness of vacuolization. 



