22 HOFMEISTER, ON 



only in one of these cells (PL IV, figs. 4, 5, 9), sometimes in 

 the cells next but one to the rooting cell (PI. 4, figs. 6, 7), 

 or even in one only of such cells. The germ-plant con- 

 sists now of the basal cell, which is protruding the first 

 radicular papilla ; of two sets of cells above the basal cell, 

 each consisting of from two to four cells adjoining one 

 another ; and of the apical cell, which is already not unfre- 

 quently divided by a longitudinal septum (PI. IV, figs. 9, 10). 



The activity of cell-multiplication in the direction of the 

 breadth of the plant increases continually towards the apex. 

 Although it never occurs more than once in the cells next 

 to the basal cell, it is a rare occurrence when it only takes 

 place in one of the next higher cells, and it is a rule almost 

 without exception that it happens repeatedly in the fourth 

 pair of cells reckoned from the basal cell upwards (PL IV, 

 figs. 12, 14). Hence the plant assumes the form (more 

 and more distinctly marked as it advances in growth) of a 

 plate widening continually towards the fore edge. In its 

 earliest youth the base, notwithstanding the smaller number 

 of its cells, is as Avide or wider than the apex. The expan- 

 sion of the lower cells, which occurs at an 'early period, 

 keeps pace up to a certain point with the increase in 

 breadth of the upper cells. But, when a month old, the 

 outline of the young plant has already assumed the shape 

 of a spatula (PL IV, fig. 14). 



The expansion of the cells adjoining the base of the 

 plant begins at the time of the protrusion by the basal cell 

 of the first rootlet ; this takes place contemporaneously 

 with the commencement of the multiplication of the cells 

 in the direction of the longitudinal axis, which latter 

 results only from the continual division of the apical cell, 

 or (as is more often the case) of the two adjoining apical 

 cells. Both cells divide contemporaneously by a very 

 oblique* longitudinal septum, upon which a similar septum, 

 inclined more obliquely, but in the opposite direction, 

 is soon imposed (PL IV, figs. 7, 8, 13). This division of 

 the terminal cells by septa alternately inclined in different 

 directions to the surfaces of the plant, is repeated con- 

 tinually, and with tolerable rapidity ; for instance, twice in 



* The longitudinal axis of the spore being considered to be vertical. 



