378 HOFMEISTER, ON 



ably larger than their neighbours (PI. LVI, fig. 12). Their 

 free wall becomes arched upwards ; the cell farthest from 

 the stem then divides by a septum inclined away from the 

 longitudinal axis of the stem. The double layer of cells 

 which rises in the form of a wall thus receives an addition 

 of a row of top cells. These continue to divide by septa 

 inclined alternately in two directions ; the result is that a 

 flat membranous cellular body is produced from the upper 

 side of the base of the leaf (PI. LV, figs. 26, 27 ; PI. LVI, 

 figs. 11, 12). This body was first observed by R. Muller,* 

 and is a kind of ligulate formation, most nearly resembling, 

 on the one hand the coronet of the perigone of the Narcissi 

 and the ligule of the grasses, and on the other hand the 

 scale in Isoetes. I shall merely call it a stipule. 



The cells of the stipule which are raised above the 

 surface of the leaf very soon divide by longitudinal septa 

 perpendicular to the upper and under side of the stipule 

 (PL LVI, fig. 9), and afterwards also by transverse septa 

 at right angles to the surfaces of the organ. This multi- 

 plication continues in the base of the stipule for some time 

 after the multiplication of the apical cells has ceased (PI. 

 LVI, fig. 11). 



At a later period the number of the cells of the organ in 

 the direction of the thickness, is increased by the division 

 of the cells of its lower portion parallel to the surface (PI. LV, 

 fig. 27; PI. LVI, figs. 11, 12). The double row of basal 

 cells sunk in the substance of the leaf does not increase in 

 number, but the cells increase considerably in size. As 

 the longitudinal growth of the stipule draws to a close, its 

 apical cells, in Selaginella Gcdeottii and others, divide 

 only by transverse septa perpendicular to the surface. The 

 upper end of the stipule becomes a simple cellular layer. 

 The margin, in all species, exhibits a delicate fringe, caused 

 by the papillate outgrowth of individual cells (PL LV, 

 fig. 28). The cells of the stipule contain granular mucilage 

 which is colourless or grey or — under transmitted light — 

 of a reddish colour. They never contain chlorophyll. 

 Like the stipules of the greater number of those phsen ogams 

 in which stipules occur, the development of the stipule of 



* 'Bot. Zeit.,'lS46. 



