SPORE-PRODUCING MEMBERS 
tissue also as tapetum. 
313 
The dehiscence is along a transverse line, and the 
preparation for this is already indicated at the distal end in Fig. 157 pb, d. 
Meanwhile, the sporogenous group within, in 
the formation of which the whole products of 
the archesporium are involved, has been subject 
to repeated cell-division: its cells finally separate, 
round themselves off, and all of them, as a rule, 
undergo the tetrad-division. In 
sporangium the form is less strongly curved 
in Z. Seago than in many other species, while 
the stalk is a relatively narrow one. 
general proportions, as well as the imperfect 
protection of the sporangium afforded by the 
rather natrow sporophylls, are shown in Fig. 
158 d, ef 
The type of sporangium thus described for 
LZ. Selago, with its single row of archesporial 
cells, relatively narrow stalk, 
protection while young, appears to. be character- 
the mature 
The 
Fic. 158. 
d, e, f=sections radial, tangential, 
and transverse of mature sporangia 
of Lycopodium Selago. g, h, t= 
similar sections of mature sporangia 
of Lycopodium phlegmaria. X12. 
and imperfect 
istic, with relatively slight modifications, of the 
sub-genus Urostachya: other species of the sub-genus which have been 
examined, viz., LZ. dichotomum, Jacq., carinatum, Desv., nummularifolium, 
Per PS ti CPT L. 
Lycop Me, . 
Radial sections of sporangia, In 
the upper, younger figure periclinal 
divisions are shown in two cells, and 
the archesporial cells are shaded. 
In the lower, older figure the pro- 
duct of division of these cells is 
shown, X 200. 
Blume, and Phlegmaria, L., are all alike in 
showing an archesporium consisting of a single 
tangential row of cells, though the number of 
these in the row may vary; the simplest case 
observed was that of ZL. Phlegmaria, where the 
single series consisted of certainly not more than 
five cells, and perhaps of less. The further 
development in these species was also the same 
as in LZ. Selago, though the proportions were 
different. In Z. dichotomum, however, there is 
the peculiarity that the sporangial wall is found 
to be more massive, consisting of 4-7 layers. 
Putting such differences aside there seems 
reason to regard the single tangential series of 
archesporial cells as a common feature of the 
sub-genus Urostachya: further, the sporangia 
ate inefficiently protected by the sporophylls 
(Fig. 158 g, 4, 7). 
In Pritzel’s arrangement of the genus the 
section Jnundata is separated from Phlegmaria, 
and placed in the second sub-genus hopalo- 
stachya. ‘We shall see that the sporangial character upholds this change. The 
sporangia are from the first more bulky than in Urostachya (F ig. 160 &, 4, m), 
