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1904] LAND—EPHEDRA TRIFURCA rT 
1903. Free nuclear division, therefore, extends through a period of 
approximately twenty days. 
Simultaneously with the appearance of walls, the gametophyte is 
differentiated into two distinct regions: a micropylar or sex-organ 
producing region, and an antipodal or nutritive region. The behavior 
of the lower part of the gametophyte is strongly suggestive of the 
same region in Gnetum Gnemon, as described by Lotsy (’99). The 
cells of the antipodal region are only slightly elongated and are fairly 
regular in outline. As growth proceeds—and it is very rapid—this 
lower part is again separated into two physiologically distinct regions: 
storage and haustorial. The storage region comprises the greater 
part of the gametophyte, and is highly charged with starch and other 
foods. In the center are a few rows of thin-walled cells containing 
much more food than the surrounding cells, and extending up to the 
base of the archegonia. It is down through this thin-walled region 
that the embryo is thrust by the elongation of the suspensor. The - 
haustorial part of the gametophyte (fig. 44) is composed of one or 
two layers of the outermost cells, which are clearly haustorial in 
function. Those at the tip of the gametophyte are elongated to a 
point ending in a single cell. The haustorial cells do not have the 
great elongation shown by the cells in the same region of Zamia. 
The storage and haustorial region increases in size as long as the 
embryo continues to grow. 
The region in the immediate vicinity of the archegonia and for 
some distance below is very loosely organized, and the cell-walls are 
extremely delicate. In the central region immediately beneath the 
archegonia instances were noted in which the walls were late in appear- 
ing. The cells of this region are very vacuolate, and in consequence 
have little contents. 
This feebly organized region is significant from a phylogenetic 
standpoint. In Tumboa the upper part of the gametophyte is loosely 
organized, and the numerous cells which function as eggs never get 
beyond the archegonium initial stage. In Gnetwm Gnemon the same 
region never gets beyond the free nuclear stage, and these free nuclei 
function directly as eggs. It is possible that Ephedra, Tumboa, and 
Gnetum show stages through which the ancestral forms of angio- 
sperms in all probability passed. 
