SUMMARY. 83 
arise in the central cell, being formed de novo in the cytoplasm either 
in close proximity to the nuclear membrane or midway between the 
nuclear membrane and cell wall. They are at first very small, being 
scarcely more than points where a few radiating filaments converge. 
No distinct granules or differentiated central organ can be detected at 
this time. 
(7) The blepharoplasts gradually increase in size, an outside sur- 
rounding membrane and vacuolated contents of different structure 
and composition being soon differentiated. They continue to grow 
until they reach a size, shortly before division, of about 18 to 20 in 
diameter. The kinoplasmic filaments, of which there were at first 
very few, increase in number until they become very numerous. The 
entire central cell and nucleus, together with the stalk cell and nucleus 
also, grow very materially in size. 
(8) The prophase of division of the central cell appears to be the same 
as in ordinary cells. In this stage the blepharoplast has reached its 
largest size and has frequently become elliptical. Its contents present 
a beautiful, regularly vacuolate structure, and stain red with safranin. 
(9) A synapsis stage is formed in the division of the central cell 
similar to the synapsis stage in the division of the pollen mother cells 
of various plants. This condition is not due to contraction, as the 
entire nucleus is filled with an unstained ground plasm which exhib- 
its a reticular structure and shows no indication of contraction. In 
the collection of the chromatin matter around the nucleolus the chro- 
matin granules apparently move along the meshes of this reticulum. 
(10) As the division approaches the equatorial-plate stage the ble- 
pharoplasts begin to break up, the contents contracting and gradually 
disappearing, while the outer membrane begins to break apart here 
and there and can be observed to be made up of very numerous gran- 
ules. The kinoplasmic filaments surrounding the blepharoplast, which 
in the previous stage had been very abundant, seem to have disap- 
peared or at least are unrecognizable from the surrounding reticulum. 
(11) The spindle is developed while the nuclear membrane is intact 
throughout, being apparently entirely of nuclear origin. In the equa- 
torial-plate stage none of the spindle fibers can be traced beyond the 
nuclear membrane, and certainly have no connection with the ble- 
pharoplast. 
(12) In an early anaphase the stainable contents of the blepharoplast 
have entirely disappeared, its place being taken by a colorless ground 
plasm. The outer membrane is more segmented and the individual 
granules of the membrane are clearly distinguishable. The nuclear 
membrane has broken down and its place is occupied by spindle fibers, 
which preserve the original shape of the nucleus. The spindle is 
fully formed now and the poles push very slightly out of the original 
nuclear limitations. There is no system of radiations surrounding the 
