CHAPTER XXIV. 
SPORE-PRODUCING MEMBERS OF THE LYCOPODIALES. 
THE normal sporangia in the Lycopodiales are always non-septate sacs, 
excepting that in the megasporangia of Jsve¢es there may be an isolation of 
the megaspore-mother-cells (see p. 320). The form is that of a kidney, of 
which the curvature and proportions are liable to considerable variation. 
The position is, as we have 
seen, essentially constant, each 
sporangium being subtended by, 
or inserted in a median position 
relatively to its sporophyll; the 
curvature isin the tangential plane, 
showing in tangential section a 
more or less pronounced fan-like 
outline. A series of examples 
of sporangia will be selected as 
illustrating the structure and 
mode of development, and the 
degree of variation in form and 
proportion which exists within 
the phylum. Fic. 156. 
The genus Lycopodium will Radial sections through young sporangia of Lycopodium 
Selago. In the youngest the whole sporophyll is shown (2), 
be taken first, and the Spor- and the axis (s¢), and it is seen that the sporangium arises 
. ; upon the surface of the sporophyll. The older stages show 
angia compared in a number the segmentation of the sporangium. X 200. 
of species. It will become 
apparent from this comparison that the differences which they show are 
not at haphazard, but that they follow with some degree of accuracy those 
lines of external differentiation, upon which the systematic arrangement of 
the genus has been based. In order to make this clear the description will 
follow the accepted systematic order, beginning with the least differentiated 
types. In Z. Seago} the sporangium originates at the base of the sporophyll, 
1Studtes, i., Pp.» 511. 
