OTHER MODES OF NUCLEAR DIVISION 215 



effect on the nutritive functions performed by the nucleus during the 

 early cleavage stages. Development did not proceed far enough to 

 warrant any conclusion regarding the effect upon the role of the nucleus 

 in differentiation and inheritance. 



Although what probably represents amitosis has been observed in 

 young germ cells, it has not been shown with certainty in any case that 

 descendants of these amitotically dividing nuclei become the nuclei of 

 normally functioning gametes. To gain conclusive evidence for such an 

 occurrence it would be necessary to trace the descendants of the amitotic- 

 ally dividing nuclei through to particular gametes or spores and then to 

 note the effect upon the individuals produced by them. This would be a 

 matter of extreme experimental difficulty, and not at all possible in 

 most organisms. If it were successfully accomplished and the individuals 

 were found to be normal in every respect, not only in the cleavage stages 

 but throughout development, the revision of the chromosome theory 

 which various workers have advised would at once become necessary. 



Bibliography 10 



Other modes of nuclear division 

 ACTON, E. 1914. Observations on the cytology of the Chroococcacese. Ann. Bot. 



28: 433-454. pis. 23, 24. 

 ARBER, A. 1914. On root development in Straliotes aioides L., with special reference 



to the occurrence of amitosis in an embryonic tissue. Froc. Camb. Phil. Soc. 17 : 



369-379. pis. 2. 

 BERGHS, J. 1906. Le noyau et la cinese chez le Spirogyra. La Cellule 23: 53-86. 



pis. 3. 



1909. Les cineses somatiques dans le Marsilia. Ibid. 25: 73-84. 1 pi. 

 BOVERI, TH. 1907. Zellen-Studien VI. Die Entwicklung dispermer Seeigeleier. 



Jena. 

 BTJSCALIONI, L. 1898. Osservazioni richerche sulla cellula vegetale. Ann. Inst. 



Bot. Roma 7. 

 BUTSCHLI, O. 1890. Ueber den Bau der Bakterien und verwandter Organismen. 



Leipzig. 

 1896. Weitere Ausftihrungen liber den Bau der Cyanophyceen und Bakterien. 



Leipzig. 



1902. Bemerkungen liber Cyanophyceen und Bakterien. Arch. Protist. 1. 

 CALKINS, G. N. 1901. .The Protozoa. New York. 

 CARTER, N. 1919. The cytology of the Cladophoracese. Ann. Bot. 33 : 467-478. 



pi. 27. figs. 2. 

 CHAMBERS, R. 1917. Microdissection studies. I. The visible structure of the cell 



protoplasm and death changes. Am. Jour. Physiol. 43: 1-12. figs. 2. 

 CHILD, C. M. 1907a. Amitosis as a factor in normal and regulatory growth. Anat. 



Anz. 30: 271-297. figs. 12. 

 1907&. Studies on the relation between amitosis and mitosis. Ill- VI. Biol. Bull 



13: 138-160, 165-184. pis. 2-10. 



1911. The method of cell division in Monezia. Ibid. 21: 280-296. figs. 16. 

 CHODAT, R. 1894. Contenue cellulaire des Cyanophyce*es. Arch. Sci. Phys. Math 



Geneve 11132: 637-641. t 

 CHUN, C. 1890. Ueber die Bedeutung der direkten Zelltheilung. Sitzber. Schr. 



Phys.-Oekon. Ges. Konigsberg. 



