428 BOTANICAL GAZETTE [JUNE 
and during prophase the linin network becomes more conspicuous and 
finally segments into 20 chromosomes. The kinoplasm around this 
nucleus is rather scanty, even after the spindle fibers are formed. 
The spindles are intranuclear. No centrosome could be found, but 
there is a concentration of kinoplasm at the two poles. 
After anaphase, the nuclear membrane dissolves and the vacuole 
intrudes into the nuclear cavity between the two sets of daughter 
chromcsomes, one set passing to the apex and the other remaining at 
the base of the sperm mother-cell. The upper part of the cell, includ- 
ing the vacuole, is then cut off as the sperm from the lower portion by 
a cleavage furrow, which crosses the cell somewhat obliquely. 
The nucleus which remains at the bottom of the sperm mother- 
cell now repeats this mitosis, forming a second sperm, and perhaps 
two or three more are developed before the antheridium ends its 
fertility. 
OOGENESIS AND FERTILIZATION. 
The mitoses in the vegetative cells of the female or cystocarpic 
plant are similar to those of the male. The number of chromosomes 
is invariably 20. 
The female organ or procarp develops from a central axial cell, 
next to the apical cell of a short lateral branch. -The central axial 
cell gives rise to a pericentral cell from which by successive mitoses a 
four-celled carpogonial branch is formed. The terminal cell of this 
series becomes the carpogonium, situated as a rule above the peri- 
central cell, owing to the curved growth of the carpogonial branch. 
The carpogonium is at first round and the nucleus lies in its center. 
While this nucleus undergoes a typical mitosis to form two nuclei, the 
carpogonium puts forth the process which is to become the trichogyne. 
After mitosis one of the nuclei proceeds into the developing tricho- 
gyne to become a trichogyne nucleus, and the other remains below 
in the carpogonium as the gamete nucleus. 
Ccincident with the development of the trichogyne, the pericen- 
tral cell gives rise to the two sets of auxiliary cells, one of which is a 
series of three or four, formed above, so that they lie just beneath 
the carpogonium, and the other series consists of two cells formed 
below. 
When the sperm comes in contact with the trichogyne, the walls 
c 
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