BNALUS ACOROIDES. 
273 
circle, the Bepals (fig. 2) has very few papillae, but rather many 
tannin cells ; the interior circle, the petals, on the contrary, 
which after the bursting of the flower becomes situated on 
the outer side, has very well-developed papillae (fig. 3), but 
rather few tannin cells. 
I have not been able to follow the development of the 
anthers and pollen grains in their earliest stages. It may be 
Fig. 3.—Transverse section of a male petal with papilla? (226x1). 
observed that in the sporangia probably only one row of 
pollen mother cells develops, as is the case in many other 
plants, for instance Knautia arvensis (c/. Goebel 9, p. 396). 
A transverse section of a ripe microsporangium shows 
always only very few pollen grains (2-3), apparently from 
the same tetrad (fig. 4). The number of the pollen mother 
with a tetrad (112x1). 
cells is not greats for in a longitudinal section there are at 
most only 8 tetrads to be seen and if always only one row 
is developed, there will thus be only very few—about 30- 
pollen grains developed in each of the four sporangia in 
every anther. The wall-layer of the anther is thin, and a 
