16 Mitosis in Pellia 



Radiations reappear during telophases. The aster is believed to be concerned in sepa- 

 rating the poles of the spindle; the radiations during the telophase may be concerned 

 in forming the nuclear membrane or a Hautschicht about the nuclear membrane. In 

 the second and third mitoses, the centrospheres and asters become more and more 

 indistinct, and in succeeding mitoses the centrosphere becomes indistinguishable, and 

 a few irregular rays replace the aster. 



3. The rays are believed to be lines of streaming material, consisting of the same 

 substance as the centrospheres. 



4. Centrosomes, centrospheres, and blepharoplasts are believed to be the same 

 structures historically, being only different manifestations of a common kinoplasmic 

 activity. 



5. No centrosomes or centrospheres were found during mitoses in the apical 

 region of the thallus or in developing antheridia. It was not determined whether a 

 blepharoplast occurs toward the close of spermatogenesis. 



6. The central portion of the spindle is believed to be derived in large measure 

 from the nucleolus. 



LITERATURE CITED 



1. Belajeff, Wl. "Zur Kentniss der Karyokinese bei den Pflanzen," Flora, Yo\. IjXXIX 



(1894), pp. 430-42, Plates 12, 13. 



2. . "Ueber die Centrosomein den spermatogenen Zellen." Ber. d. deutsch. hot. Gesell., 



Vol. XVII (1899), pp. 199-205, Plate 15. 



3. Campbell, D. H. The Structure and Development of the Mosses and Ferns. New York, 



1895. 



4. Chamberlain, C. J. "Oogenesis in Pinus Laricio." Bot. Gazette, Vol. XXVII (1899), pp. 



268-80, Plates 4-6. 



5. Davis, Bradley M. "Kerntheilung in der Tetrasporenmutterzelle hei Corallina officinalis 



L. var. mediterranea." Ber. d. deutsch. bot. Gesell., Vol. XVI (1898), pp. 266-72, Plates 

 16, 17. 



6. . "The Spore Mother-Cell of Anthoceros." Bot. Gazette, Vol. XXVIII (1899), pp. 



89-109, Plates 9, 10. 



7. . "Nuclear Studies on PelHa." Ann. Bot., Vol. XV (1901), pp. 147-80, Plates 10, 11. 



8. Farmer, J. B, "Studies in Hepaticae: On Pallavicinia decipiens. Mitten." Ibid.,\o\. 



VIII (1894), pp. 35-52, Plates 6, 7. 



9. Farmer, J. B., and Reeves, J. " On the Occurrence of Centrospheres in Pellia epiphylla, 



Nees." Ihid. (1894), pp. 219-24, Plate 14. 

 10. Farmer, J B. "On Spore-Formation and Nuclear Division in the Hepaticae." Ihid., Vol. 



IX (1895), pp. 469-523, Plates 16-18. 



11 . " Ueber Kerntheilung in Lilium-Antheren, besonders in Bezug auf die Centroso- 



menfrage." Flora, Vol. LXXX (1895), pp. 56-67, Plates 2, 3. 



12 Farmer, J. B., and Williams, J, L. "Contributions to Our Knowledge of the Fucaceae: 



Their Life History and Cytology." Phil. Trans. Roy. Soc. London, Vol. CXC (1898), 



pp. 623-45, Plates 19-24. 



13. Ferguson, Margaret C. "The Development of the Pollen Tube and the Division of the 



Generative Nucleus in Certain Species of Pines." Ann. Bot., Vol. XV (1901), pp. 193-223, 



Plates 12-14. 



342 



