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1903 | GAMETOPHYTES AND EMBRYO OF TAXODIUM 127 
and five above. An abnormal condition is shown in fig. 728. 
Here two of the eight nuclei produced by the third division 
have not joined in the formation of the basal group, but remain 
some distance above, quite separate from the proembryo beneath. 
Two nuclei are at the base in this case, as usual, but the number 
above is only four, thus making up the total eight. All these 
nuclei are in division. The settion is somewhat oblique, so that 
the base of one of the upper cells is shown above the two basal 
cells. 
After the cells are arranged as mentioned, they become 
separated from each other by delicate cell walls, the upper tier 
remaining open at the top. The fourth division now takes place 
almost simultaneously in all of the nuclei. The axes of the 
spindles in the upper tier are parallel with the axis of the arche- 
gonium (fig. 727). There is thus cut off from the upper cells 
an equal number of nuclei which lie free in the cytoplasm of the 
egg and form the rosette (fig. 729). Cell walls are produced 
by this division and the middle tier is now completely closed 
(fig. 129). By referring to fig. 727 it will be seen that the 
starch is all grouped in the base ends of the upper tier of open 
cells, and that the lower poles of the spindles are imbedded in 
it. When walls are formed all the starch is inclosed in the 
middle tier with the exception of a few scattered grains in the 
tip cells. The spindles in the lower cells lie at right angles to 
the ones above, and form a tier of four cells, or of six in those 
cases where three original cells have been arranged at the tip, or 
only two where there is but one tip cell. The middle tier now 
elongates into the suspensors ( fig. 733), the nuclei and most of 
the cytoplasm appearing at the lower end. Further division in 
the tip cells does not occur until the suspensors have greatly 
elongated. 
The formation of the embryo proper shows much varia- 
tion. The suspensors from a single archegonium only rarely 
remain completely united at their tips, but usually separate more 
or less. The supernumerary suspensors are left behind at 
various positions, so that at the time of the first division of the 
tip cells the number of suspensors and tip cells is usually the 
