192 Mr J. M. Macfarlane 07i the 



The Siructure and Division of the Vegetable Cell. By J. 

 M. Macfarlane, B.Sc, Demonstrator of Botany in 

 the University of Edinburgli, (Plates IX. and X.) 



(Read April 16 and May 12, 1881.) 



Introduction. 



During the last six years our knowledge of the animal 

 and vegetable cell has been greatly increased. Previously, 

 it was held by most observers that a typical cell consisted 

 simply of a loall or bounding membrane, secreted from the 

 protoplasm which filled the cell, a nucleus formed of proto- 

 plasm of a denser consistence than the surrounding mass. 

 Inside the nucleus a nucleolus was supposed occasionally to 

 be present. It is now being gradually discovered that the 

 cell is of a more complicated nature, and is the centre of 

 more complicated changes than had once been imagined. 

 Admirable summaries of the advances made prior to 1878, 

 especially those of Strasburger, have been given* by Priestley 

 and Klein. To summarise briefly their papers, it may be 

 said that a network of fibres can be seen permeating the 

 substance of the cell attached on the inner surface to 

 the nucleus, and that these are merely continuations of a 

 similar network within the nucleus. The former has been 

 termed by Klein the intra-cellular network, the latter, the 

 intra-nucleor netivork. It is further stated by Klein that 

 Eimer, Flemming, and himself consider that in the animal 

 cell a nuclear membrane is present surrounding the nucleus. 



As it is specially with the vegetable cell that I will deal, 

 a more detailed account of Strasburger's investigations is 

 necessary.f This author shows that in division of the cell 

 the nucleus undergoes a series of peculiar changes. At 

 first of a rounded or oval outline, the denser material 

 aggregates to form a dark band — the nuclear plate — cross- 

 ing a clear fusiform area — the nuclear disc. The former 

 splits up, each part retreating along the clear area to its 

 extremity, and there form the daughter nuclei. These are 

 again united by a fibrous bridge, and in the middle of this 

 a row of granules appear — forming the cell-plate — which 



* Quart. Joiirn. Micro. Soc. vols. xvi. and xviii. 

 t UeLer Zellbildung uud Zelltlieilung. 



