138 Gager . — The Development of the Pollinium and 
pointed at both ends, and much longer and more acuminate 
at one pole than at the other (Fig. 32). The more tapering 
pole appears to be somewhat bent to one side, but this was 
doubtless caused by the shoving of the microtome knife, or 
by some other mechanical injury. The difference in the 
length and manner of tapering of the two ends does not 
seem to be due to the way the section was cut, as the poles 
seem well defined and pointed at both ends, and not truncate 
at one end as would be expected had the microtome knife 
cut off one pole. Here also the nucleus was too tiny to 
permit of the details of spindle-formation, &c., being clearly 
made out. 
The nucleus of the larger cell at this period possesses 
a rather conspicuous, vacuolated nucleolus, with a well-defined 
membrane, and a prominent nuclear reticulum. It would 
seem as if this division takes place rather rapidly, for in 
over ten thousand pollinium-cells examined, at a time when 
this division would be expected, only the single instance 
figured was found. 
Cell-division follows the division of the nucleus of the 
smaller cell, each daughter-nucleus organizing about itself 
a portion of protoplasm, forming two cells, which later prove 
to be the sperm-cells. These cells remain enclosed by the 
delicate wall which originally surrounded their mother-cell 
(Fig. 33). No instance was found where any of these 
pollinium-cells failed to develop, as Schleiden ( 1849 ) has 
described. 
Germination of the Pollinium-Cells. 
When the pollinia are deposited on the stigma, or placed in 
a suitable germinating medium, the outer wall bursts after 
a time, and the fertilization-tube protrudes (Figs. 34, 35). 
Brown ( 1833 ) states that this tube does not branch, but the 
writer found rare instances of the branching of the tube in 
the tissue of the style. 
The nucleus of the larger cell enters the fertilization-tube 
in advance of the sperm-cells, and the latter remain close 
