On THE PITHOPHORACES. 13 
of a parting wall, which is to divide the mother cell of the spore into 
two daughter cells. The foundation of this parting wall is laid, in P. 
kewensis fob., not at the point where the cask-shaped widening of the 
cell commences, but a small space below this point (pl. 3, fig. 7 w’, ba). 
The parting wall first appears as a narrow ringformed ledge on the 
inside of the original membrane of the cell. This rimgformed ledge in- 
creases successively inwards, so as to grow broader and broader (pl. 3, 
fig. 7 ba), and the hole in its centre consequently narrower and narrower; 
till it is at last completely filled up, and thus the parting wall quite com- 
pleted. By this parting wall the mother cell is now divided into two 
daughter cells, an upper one rich in chlorophyll and cask-shaped, the 
spore, and a lower one, containing but little chlorophyll and cylindrical, 
the subsporal cell. The spore which has been formed in this manner, 
is completed by its membrane growing so much thicker, that it is at 
last, in P. kewensis nob., twice or thrice as thick as it originally was 
(pl. 3, fig. 9). A formation of clearly discernible layers in the mem- 
brane does not take place here. The contents of the cell do indubit- 
ably also undergo a change, for its colour, originally of a dark green 
or almost blackisk green, changes into brown, probably by a part (or 
all) of the granules of starch being transformed into a brownish oil. 
By this exposition it_is shown, that in the formation of spores in 
P. kewensis nob. the following four stages may be distinguished: l:o The 
cask-like widening of the upper part of the mother cell of the spore: 2:0 
The passing of the chlorophyllaceous matter from the lower, cylindrical 
part of the cell to its upper, cask-like part; 3:0 The appearing, just 
below the cask-shaped widening, of a succedaneously formed parting 
wall, and 4:0 The ripening of the spore, situated above the parting wall, 
by the thickening of the membrane and the transformation in part of 
the contents of the cell.— The result of the whole process consequently 
is, that the mother cell of the spore forms, by division into two, one cell 
capable of germinating, the spore, in the formation of which the whole 
chlorophyllaceous contents of the mother cell are consumed, and one 
vegetative cell, the subsporal, which is not capable of further formation 
of cells or increase of any kind, being devoid of protoplasm, and which 
may consequently be regarded as being at. least half dead. 
If you compare the other species of Pithophoracee with P. kewensis 
nob. as to the process of the formation of spores, you will find, that 
the formation of spores takes place, upon the whole, much in the same 
manner, but withal that a couple of less essential deviations may occur, * 
