" The Nucleus In Plant Cells," 



BEING THE 



PRESIDENTIAL ADDRESS 



Delivered to the Liverpool Microscopical Society 

 on 22nd January, 1909, 



BY 



ARTHUR H. DUDLEY. 



The greatest incentive to microscopic investigation, and 

 attended by such splendid results during the latter half 

 of last century, is to be found in those researches 

 which established the " CELL " to be the structural and 

 physiological unit of the organism — plant or animal 

 (Fig. I). 



Interest first centered around the wall as the essential 

 part of the cell, later, when some cells (" globules ") were 

 found which never formed walls, it was transferred to the 

 viscid contents of the cell, and finally to the nucleus as its 

 functions came to be understood. 



The discovery of the nucleus in plant cells is ascribed 

 to Robert Brown, an eminent English botanist, in 1833, 

 although it seems to have been observed by Fontana in 

 1 78 1. He first found it in the epidernial cells of some 

 orchids, then in their pollen cells and in cells of numerous 

 other plants, both Monocotyledons and Dicotyledons. 

 His investigations, together with those of Schleiden and 

 Schwann,^ the founders of the cell-theory, and other 



