1901] SPOXANGIA AND GAMETOPHYTES OF SELAGINELLA 179 
7. Abortive sporangia are to be found at the base of the strobilus as in 
many species of Lycopodium. 
With regard to the derivation of the sporogenous tissue, 
repeatedly radial sections show a distinct plane of segmentation 
separating the sporogenous tissue into two such definite regions 
that it is difficult to avoid the conviction that each complex is 
the progeny of two independent cells. The term ‘‘archesporium ” 
is used by Bower to signify the lower cell or cells. I have used 
the term to indicate the superficial cell itself. With regard to 
the fourth statement, my observations on S. apus do not agree. 
With the fifth and sixth statements, as regards the origin of 
the tapetum, my observations are in accord. The seventh 
statement I find true of S. rupestris, but not of S. apus. 
In no particular do my preparations agree with Campbell’s 
figures of the sporangial development of S. Kraussiana. 
Of no little interest is the incomplete septum in the micro- 
sporangium of S. rupestris, which arises above the pedicel. In 
vertical section, the resemblance to the celebrated fossil Lepzdo- 
dendron Braunti, as figured by Bower (see his plate 48, fig. 100), 
is very marked. He discusses in the accompanying text the 
possible function of this region of the sporangium. ‘ Possibly,” 
he says, ‘‘ these extensions of sterile tissue may have facilitated 
the nutrition of the developing spores, or they may perchance 
have contributed to the mechanical support of the sporangial 
wall.”” In connection with the former theory, it is noteworthy 
that this septum is found only in the microsporangium, where 
some of the spores are remote from the tapetum. A feature 
that may have some bearing on this point is the fact that the 
megaspore mother cell, so far as I have observed, is always near 
the periphery of the sporogenous mass and never at the center, 
a favorable position to secure nutrition from the tapetum. Scott 
in his Studies in fossil botany, 1900, says, & propos of this feature 
in Lepidostrobus Veltheimianus, ‘this structure may be compared 
with the trabeculae of Isoétes. It is best shown in the miicro- 
sporangium, but may have originally been present in the mega- 
sporangia also.” 
