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THE AMERICAN NATURALIST. [VOL. XXXIX. 



reminding one of the central spindle of a mitotic figure (Fig. 

 1 6, c). In general the two types of protoplasmic connections are 

 not found together in the same cell or tissue. 



A new point of view was introduced into the discussion by 

 the very important paper of Strasburger, in 1901. He consid- 

 ered the protoplasmic connections as sufficiently clearly differ- 

 entiated structures to rank as organs of the cell and proposed 

 for them the name plasmodesmen. Strasburger in agreement 



FIG. 16. Protoplasmic connections between cells of plants, a, endosperm cells of Strych- 

 nos nux vomica ; 6, details of the solitary fibers in the same form, (m) middle lamella ; c, 

 grouped fibers at bottom of pit in endosperm of Phytelephas and crossing the pit mem- 

 brane in a spindle-shaped figure : d, cell connections around the sporophytic portion of a 

 developing cystocarp of Champia, (s) sporophytic elements ; e, fibers between cells of 

 Cladophora; f, cell connections around the ascogenous elements in Laboulbenia ; g, 

 clamp connections in Pleurotus (a, after Tangl, *7q-'8i; b and c, Kohl, :oo; d, Davis, 

 '96 b; e, Kohl, : 02 ; f, Thaxter, '96 ; g, Meyer, :o2). 



with Kienitz-Gerloff opposed the view that the plasmodesmen 

 were in any way derived from or related to the spindle fibers 

 associated with the formation of cell plates. He believed them 

 to be developments of the outer plasma membrane as he like- 

 wise considers the cilia in certain zoospores (see account of 

 zoospore and sperm in Section III, Amer. Nat. vol. 38, pp. 571, 

 576, 1904). Strasburger also holds that pores are formed in the 

 cell walls by the fermative activities around plasmodesmen. A 



