Sporangium-bearing Organs of the Lycopodiaceae. 49 
a perfectly compact cone is formed, on the outside of which no 
signs of the sporangia are visible (PI. II., Fig. 9a). The outer cell- 
walls of the sporophyll epidermis are provided with a cuticle which 
is everywhere thickened, but especially on the abaxial surface of 
the basal part of the dorsal flap 1 . Here (e, Text-fig. 8, XI.), it seems 
to be of use in dragging apart the sporophylls, when they separate 
to let loose the spores. 2 The sporangium dehisces by means of a 
slit, which is placed laterally on the abaxial side, thus liberating 
the spores in the position most favourable for their dissemination. 
There is a large mucilage cavity in the sporophyll stalk, running 
in a longitudinal direction beneath the vascular bundle. 3 The 
pedicel of the sporangium is made up of short cells whose walls are 
strongly lignified in transverse bars 4 , (PI. III., Fig. 7), and present a 
very striking appearance if stained with Iodine green and Eosin, 
when they are seen to be made up of alternate patches of pink and 
green. No connection can be traced between these cells and the 
vascular elements of the trace which supplies the sporophyll, but 
only one or at most two layers of cells separates the two tissues. 
IV.— Classification. 
It appears from the above description that the classification of 
the genus Lycopodium according to Pritzel is in the main supported 
by a study of the sporophylls of the various species. Throughout 
the Urostachya the sporangium is axillary in position, on a sessile 
sporophyll; in the higher groups of the Rhopalostachya the sporan¬ 
gium takes its origin from the stalk of a peltate sporophyll. 
In the Inundata, the first group of the Rhopalostachya, an 
intermediate condition is maintained. The sporophylls are stalked 
and are furnished with a dorsal flap, but the sporangium is axillary 
in L. inundatum and almost axillary in L. carolinianum. It does not 
1 cf. Goebel, Organography II., p. 580. 
3 Experiments have been made on the cones of L. cernuum. 
Cones taken from spirit and herbarium material were soaked 
water and then were (1) dried in air, or, (2) placed in strong 
glycerine. In both series of experiments each sporophyll was 
gradually drawn backwards, at the same time folding its edges 
together over its dorsal surface, thus exposing the sporangia. 
Sections were also examined microscopically in strong gly¬ 
cerine. The lignified cells at the base of the sporophyll were 
seen to gradually contract and an air bubble finally appeared 
in each cell. 
3 cf. T. G. Hill, 1906. 
4 cf. Transfusion tracheides in Stigmarian rootlets, Weiss, F. E., 
1904. 
