CELL FORMATION BY UNION. 49 



B. — Formation of Vegetative Cells. 



1. By the progressive formation of a division wall. 

 3. By the simultaneous formation of a division wall. 



The main objection to this classification is that its principal divis- 

 ions are based upon physiological distinctions alone. 



(6) Duchartre, in liis " Elements de Botanique," makes a very sim- 

 ple classification, as follows : 



A. — Free Cell-Formation. 

 1 Intracellular. 



2. Extracellular [Rejuvenescence]. 



B.— Formation of Cells by Division. 

 1. Progressive division. 



3. Simultaneous division. 



Note on Paragraph 66. " From the researches of Schmitz on the 

 Myxomycetes (Sitzber. d. nieder-rheiu. Ges. in Bonn, 1879), it appears 

 that the nuclei of the cells which coalesce to form the Plasmodium do 

 not fuse, but remain distinct ; this case of coalescence of cells cannot, 

 therefore, be any longer regarded as an instance of cell -formation by 

 conjugation." (8. M. Vines in App. to Sachs' Text-Book of Botany. 

 Second English Edition, p. 945.) 



