DEVELOPMENT OF THE POLLEN TUBE AND PROTHALLUS. 31 
the central cell has increased in size to about twice the diameter it 
bad immediately after its reorganization, the blepharoplasts first begin 
to appear. (Compare figs. 19 and 24.) In Zamia floridana in 1898 
the blepharoplasts appeared mainly between March 5 and March 15, 
while in Z. pumila the same year they appeared mainly between March 
10 and 25. It is probable that the date of their appearance may vary 
somewhat in different years, and the time of their appearance in differ- 
ent plants and even in different ovules of the same cone is very varia- 
ble: Indeed, great difference has been noted in the time of their 
appearance in different pollen tubes in the same nucellus. It is inter- 
esting to note that the pollen tubes have considerable individuality 
apparently, and vary greatly in their stage of development, size of 
organs, etc. In tubes on the same nucellus the writer has found in 
some the fully developed spermatozoids, while in others the central 
cell had not yet divided. 
In the earliest stage in which the writer has been able to surely 
recognize the blepharoplast, it seems to be made up of a small, deeply- 
staining granule from which several filaments of kinoplasm radiate, 
following the meshes of the reticulum. The central granule does not 
seem to be different in substance from the radiations—stains the same 
and shows no differentiation ot structure. In this stage it is only a 
half micron in diameter or less and seems to be scarcely more than the 
point of crossing of the filaments of kinoplasm. They are located in 
the cytoplasm about halfway between the nucleus and the cell wall. 
Two are formed in each central cell at the same time and apparently 
independently. They are commonly located on opposite sides of the 
nucleus, but in a number of cases in this stage and in a still later 
stage they have been found nearer together, frequently less than 45° 
apart (figs. 19 and 25). The cytoplasm at the time the blepharoplasts 
appear forms a loose, open, reticular structure, and the rays which 
extend out from the blepharoplasts seem to run into the walls of 
the reticulum. The rays in this early stage are comparatively few 
and short. The nuclear plasm shows a reticular structure much finer 
than that of the cytoplasm and surrounds a large nucleolus. In the 
several instances of this early stage of the blepharoplast which have 
been observed they are located about midway between the nuclear 
membrane and the cell wall. In what seems to be a slightly later 
stage, however, when the blepHaroplasts have grown considerably 
in size and show a distinct spherical body at the point of the converg- 
ing rays, they are found quite close to the nuclear membrane, which 
is commonly slightly indented just below them (fig. 19). 
In Cycas, according to Ikeno (70, p. 571), the two blepharoplasts 
appear in the central cell shortly after the division which gives rise to 
this cell and the stalk cell. They arise as two small bodies which at 
first lie close to the wall of the nucleus. No radiations are visible 
