BEHAVIOR OF THE POLLEN TUBE 91 
ductive tissue for the pollen tubes. When young the cells of this 
tissue are of an approximately cubical or columnar form ( fig. 7) 
with thin walls. As the ovule develops they change into deep 
columnar cells with thick walls excepting at their inner ends ( fig. 
5), where the basal and lateral walls for a little distance are thin. 
The contents of these cells are more dense than those of the deeper 
lying cells and the. cytoplasm is very finely granular. Their nuclei 
are large with very finely divided chromatin. These cells appear 
to correspond in general with the cells 
described by Capus (2) as occurring at 
the base of the funicle in Dracaena ele- 
gans and by Dalmer (3) in the placenta 
of Mahonia aquifolium. From. those in 
Dracaena, however, the cells in Diodia 
teres and Richardsonta differ in having 
thick walls, and from those in Mahonia 
in the fact that they do not secrete the 
mucilage which, according to Dalmer, 
serves as food for the pollen tube. They 
are not glandular cells, but, strictly 
speaking, cells of a conductive tissue as - 
is shown by the behavior of the pollen 
tube towards it. With reference to the 
strophiole it may be remarked that this 
organ is present in other members of the 
same family, but that, so far as known, 
in no other is such a special tissue pres- 
ent, excepting as we shall see beyond | 
in Diodia Virginiana. On the upper side Fis. 8. ies ge nd 
ofthe funicle these cells have somewhat i pd F e bé whe = 
different dimensions from, but otherwise 
are exactly like those of the lower side where they have the longest 
ongitudinal diameter (tert figs. 8 and 9). Here the strophiole 
lies against the ovules so as completely to close the micropyle. 
It will be seen that there is thus formed a collar of columnar epi- 
dermis which is continuous around both sides of the funicle and, 
as will be shown, completes the path of the conductive tissue 
from the style to the micropyle. 
